Abstract:

Based on rigorous process simulation in Aspen Plus, energy optimization is conducted on the gas fractionation system in a light ends recovery unit, with a focus on exploring the effects of feed temperature and reflux ratio on system energy consumption. Considering the relative surplus of low temperature heat in refineries, the bottom temperature of deethanizer and debutanizer towers are reduced based on process analysis and distillation sequence optimization to improve the mismatch between heat sources and heat sinks. The improved gas fractionation processes integrating with hot medium water system and heat pump system are proposed to reduce device energy consumption of the unit, and a comparative analysis is conducted on the energy efficiency and economy before and after the improvement. The results obtained show that all four improved schemes could reduce the energy consumption of the unit by more than 15.61% and achieve an annual income of over 1.518 million yuan. The improved scheme integrating with hot medium water system reduces exergy consumption by 0.52 MW and 40.95%, with an annual income of 4.0057 million yuan and a payback period of 0.42 years. The improved scheme integrating with direct heat pump system has the best effect, with a reduction of 0.67 MW and 53.04% in the usage of exergy and an annual income of 4.9818 million yuan, with a payback period of 1.41 years.

Key words: heat integration, light ends recovery unit, gas fractionation system, energy optimization, energy analysis model, economy analysis model, direct heat pump, indirect heat pump

摘要：

针对轻烃回收装置气体分馏系统进行模拟分析与用能优化，并基于Aspen Plus流程模拟，探讨了进料温度、回流比对系统能耗的影响。考虑到炼化低温余热相对富余，结合工艺分析和精馏序列优化，并改善热源、热阱的不匹配性，降低脱乙烷塔和脱丁烷塔塔底温度，提出了集成热媒水系统、热泵系统的气体分馏改进工艺以降低装置能耗，并对改进前后的能效和经济性进行了对比分析。结果表明：4种改进方案均可降低气体分馏系统能耗15.61%以上，年净效益151.80万元以上。集成热媒水系统的改进工艺耗量降低0.52 MW,降幅达40.95%,年净效益400.57万元，投资回收期为0.42 a。集成直接式热泵系统的改进工艺方案改进效果最佳，过程耗量降低0.67 MW,降幅达53.04%,年净效益498.18万元，投资回收期为1.41 a。

关键词: 热集成, 轻烃回收装置, 气体分馏系统, 用能优化, 能效分析模型, 经济分析模型, 直接式热泵, 间接式热泵