己内酰胺聚合装置萃取蒸发系统节能改造技术经济分析

Technical and economic analysis on energy saving and consumption reduction of extraction evaporation system in caprolactam polymerization unit

以60 kt/a己内酰胺聚合装置萃取蒸发系统为例,探讨了影响萃取蒸发系统蒸汽消耗的因素,分析了装置节能改造的方案和效果。结果表明:影响己内酰胺聚合装置萃取蒸发系统蒸汽消耗的因素包括萃取水量、萃取水温度、蒸发回流量、蒸发浓缩液固含量;采用三效蒸发+浓缩液闪蒸技术对60 kt/a己内酰胺聚合装置进行改造,同时控制萃取水浴比为0.91、萃取水温度为110℃、蒸发回流量为900 kg/h、浓缩液固含量为86%,聚酰胺6切片中可萃取物含量控制在0.6%以内,每年可节约能耗3.48×10^(7) MJ,降低总成本151.41万元。

Taking the extraction evaporation system of a 60 kt/a caprolactam polymerization unit as an example,the factors influencing the vapor consumption of extraction evaporation system were discussed,and the scheme and effect of energy-saving transformation of the unit were analyzed.The results showed that the factors affecting the vapor consumption of the extraction evaporation system of caprolactam polymerization unit included extraction water quantity and temperature,evaporation reflux,solid content of evaporation concentrated solution;and the energy consumption was saved 3.48×10^(7) MJ annually and the total cost was reduced by 1.5141 million RMB yuan when the 60 kt/a caprolactam polymerization unit was revamped by three-effect evaporation technology combined with concentrated solution flash technology and the process conditions were controlled as follows:extraction water bath ratio 0.91,extraction water temperature 110℃,evaporation reflux 900 kg/h,solid content of concentrated solution 86% and extractable in polyamide 6 chips within 0.6% by mass fraction.