连续膜系统在碱液回收中的应用

Application of continuous membrane system in alkali recovery

为了改进粘胶短纤维生产中碱液回收过程纳滤膜系统的批量间歇的运行方式,采用六级纳滤膜系统逐级循环过滤,并结合DCS控制系统,研究开发了一种连续膜处理方法。当其中某级纳滤膜通量降低需要清洗时,可将该级纳滤膜组件从纳滤膜系统中切换出来进行清洗,其他各级纳滤膜组件正常运行,达到不停机清洗纳滤膜的目的。结果表明,碱压榨液经过连续膜处理后,产生的净液半纤含量≤5 g/L、浓缩液半纤含量达到70~75 g/L,可回收到生产系统调配浸渍碱、溶解碱。对比批量间歇运行方式,每天纳滤膜系统的清洗次数可减少2~3次,单只膜的处理量提升1.2倍。

In order to improve the batch intermittent operation mode of nanofiltration membrane system in the process of alkali recovery of viscose staple fiber production,a continuous membrane treatment method was developed by using the six stage nanofiltration membrane system for progressive circulating filtration and combined with DCS control system.When the flux of a certain stage of nanofiltration membrane decreases and needs to be cleaned,of this stage nanofiltration membrane module can be switched out of the nanofiltration membrane system for cleaning,and other stages of nanofiltration membrane module operate normally to achieve the purpose of cleaning the nanofiltration membrane without stopping the machine.The results showed that after the continuous membrane treatment,the semi fiber content of the clean liquid produced by the alkali squeezing liquid was≤5 g/L,and the semi fiber content of the concentrated liquid was 70~75 g/L,which could be recycled to the production system to mix impregnated alkali and dissolved alkali.Compared with batch intermittent operation mode,the cleaning times of the nanofiltration membrane system can be reduced by 2~3 times per day,and the treatment capacity of a single membrane can be increased by 1.2 times.