Study On Water System Cascade Utilization And Optimization In Paper Mills

Papermaking industry is not only an important basic raw material industry, but also anindustry of high water consumption and wastewater emissions. With the rapid development ofthe papermaking industry, papermaking mills increasingly face a scarcity of water resourcesand environmental pressures. How to use water reasonably and efficiently to increase thewater reuse rate is the fundamental way to alleviate the water supply and demandcontradiction.After the base research of present water-using situation, this paper proposed anintegrated water-saving optimization method of papermaking water system based onindustrial ecology theory and circular economy theory. With the guidance of this method,research on water cascade utilization and optimization of papermaking water system was alsoconducted to improve the water using efficiency and reduce the fresh water demand andwastewater discharge.Based on the papermaking water symbiosis theory, a water cascade utilization systemwas established between a tissue paper mill and a kraft paper mill. The effluent of tissue papermill was used to take place of fresh water in kraft paper mill. Experiments were carried out inthe two paper mills. The influence of process parameters on kraft paper sheet properties andpaper machines runnability were investigated. The problem of foams and spots were foundand analyzed, the solution was proposed as well. The results showed that water cascadeutilization system can be carried out between these two paper mills to reduce the fresh waterdemand and wastewater discharge through simple process and rebuilt equipments.On the basis of the feasibility of water reusing between the two mills, a water cascadeutilization system was also established in an integrated mill containing cultural paper, tissuepaper and gray paperboard. Water pinch technology was applied to the diagnoses andoptimization analysis of this water cascade utilization system. The optimal water-usingnetwork is designed. The result showed that42.9%of fresh water can be saved by theoptimized water network and that the water saving effect is fairly remarkable.