湿法腈纶五效减压蒸发工艺的改进

Innovation of five-effect underpressure evaporation process for wet-spun PAN fiber

从设备与工艺两方面分析了湿法腈纶溶剂蒸发装置蒸发处理量达不到设计值的原因，并提出了改进措施。结果表明：溶剂蒸发装置采用五效减压蒸发工艺，蒸发一至四效运行正常，蒸发五效运行不正常，存在跑料现象，导致装置蒸发处理量达不到设计值；蒸发五效的捕沫网端面不平，密封性差，导致其运行异常；通过对蒸发装置进行碱洗，修复蒸发五效捕沫网的端面，优化控制蒸发五效液位为40％～60％，装置蒸发处理量达到设计值87m^3／h，冷凝液硫氰酸钠含量达到控制指标，且蒸汽消耗降低4％。

The reasons for the evaporation content below the designed value of solvent evaporation system for wet-spun PAN fi- ber were analyzed from the aspects of equipments and process. The corresponding measures were put forward. The results showed that the solvent evaporation system adopted five-effect underpressure evaporation process in which the one- to four-effect evapora- tors run normally, but the five-effect evaporator run abnormally and the material running caused the evaporation content below the designed value ; the five-effect evaporator run abnormally due to an uneven mist eliminator end and poor sealing performance ; and the evaporation content reached the designed value 87 m^3/h, the sodium thiocyanate content satisfied the control index, and the steam consumption reduced by 4% as the evaporation system was subjected to alkali washing, the end of the mist eliminator of the five-effect evaporator was repaired, and the liquid level of the five-effect evaporation was optimized as 40% -60%.