化机浆碱回收中非过程元素氯和钾的来源、影响以及去除方法

Source, influence and removing method of non-process chlorine and potassium in alkali recovery process of chemimechanical pulping

化机浆系统中非过程元素氯和钾主要来源是主原料(木材)、清水和副原料(化学品),其会在生产系统中积累,造成碱炉燃烧时碱灰熔点下降,进而加速锅炉受热面积灰和结焦,造成碱炉运行周期缩短,生产效率下降.氯含量累积升高也会造成系统中设备和管道的腐蚀.如何降低非过程元素氯和钾的积累成为急需解决的问题.一些大型浆厂近几年已有实际应用的除氯、钾系统,包括:析滤、蒸发/结晶、冷却结晶和离子交换等方法,而目前应用较多的是蒸发/结晶法.

In chemimechanical pulping system, the main sources of non-process elements chlorine and potassium are from wood, clean water and chemicals. Chlorine and potassium accumulate in the production system, causing the alkali ash melting point decreasing when the alkali furnace burns, which causing more alkali ash and crystallization in the heating area, resulting in alkali furnace operating cycle shortened and production efficiency decreased. Increased chlorine levels can also cause the corrosion with equipment and pipes in the system. How to reduce the accumulation of non-process elements of chlorine and potassium has become an urgent problem to be solved. Some large pulp mills have developed some practical applications for chlorine and potassium removal, including filtration, evaporation/ crystallization, cooling crystallization and ion exchange methods. At present, evaporation / crystallization method is more popular and widely used.