In the kraft chemical recovery process, the accumulation of non-process elements in the system will cause corrosion damage to the equipment, which affects the normal operation of equipment. These non-process elements are mainly chlorine and potassium. The content of chlorine and potassium in the pulping system can be reduced by removing chlorine and potassium from the alkali ash in the alkali recovery boiler. The chlorine and potassium removal system is used to evaporate and crystallize alkali ash solution for separating the useful salt from non-process elements, which achieves the purpose of chlorine and potassium removal.