From manual sampling to real-time control, Valmet transforms sun paper’s chemical recovery

The two parties officially signed the cooperation agreement in January 2025, with equipment installation and successful commissioning completed in September the same year. Previously, the recovery boiler and causticizing section at Nanning Sun Paper adopted the traditional periodic laboratory sampling mode, which suffered from long testing cycles and significant manual errors, failing to meet the demands of refined process regulation.

Since the commissioning of Valmet Alkali R, the measurement frequency of key indicators has been greatly improved; the measurement frequency of reduction rate has increased by 56 times, while core parameters including total alkali, active alkali, and causticizing efficiency have seen a 2-fold increase in testing frequency. Adopting the same measurement principle as laboratory testing and equipped with fully automatic titration technology, the equipment ensures high measurement accuracy and greatly enhances data repeatability. The cooperation also included full-process installation guidance, start-up commissioning, and professional technical training to guarantee the long-term efficient and stable operation of the equipment.

"We chose Valmet’s Alkali R primarily for its leading technological heritage and proven industry application track record," commented the chemical pulp production team of Nanning Sun Paper. "The equipment has driven our leap from manual periodic sampling to full-process continuous visual monitoring. In the past, key indicators such as total alkali, active alkali, and causticizing efficiency were only tested 2 to 4 times per shift at intervals of 2 to 4 hours, forcing process adjustments to rely solely on operators’ experience. Now, all parameters are displayed in real time on the central control screen with automatic data updates every 10 to 30 minutes, making process trends intuitive and controllable.

Once fluctuations occur in white liquor causticizing efficiency or sulfidity, onsite staff can instantly adjust lime dosage or air supply volume to avoid quality deviations in advance. Meanwhile, the equipment fills the monitoring gap for critical parameters including sodium sulfide and reduction rate. With online measurement data of Na₂S and reduction degree, the air distribution in the recovery boiler reduction zone can be precisely optimized.

Currently, the daily reduction rate of the recovery boiler remains steady between 89% and 94%, staying above 90% in the optimal process range under normal operating conditions, ensuring safe and stable boiler operation. Additionally, the excess lime in causticizing is controlled at 0.61%, close to the theoretical optimal level. It not only reduces the workload of laboratory personnel but also serves as an intelligent monitoring tool for the stable operation of the chemical recovery process."

Pan Zhifeng, South Regional Sales Director of Valmet Automation Business Line, stated; "We are honored to gain recognition and trust from Nanning Sun Paper and join hands to advance the intelligent transformation of the pulp chemical recovery process. The core value of this cooperation lies in transforming laboratory precision testing capabilities into industrial online intelligent applications, delivering accurate data support for production process optimization.

By adopting the identical testing principle and automatic titration technology as laboratories to eliminate human errors and deploying a dedicated project team to provide end-to-end technical services covering installation, commissioning, and operation & maintenance, we ensure immediate results upon project delivery, effectively helping enterprises improve process stability and reach production economic benefits."

The successful implementation of this project stands as an important milestone for Valmet to further deepen its presence in Guangxi’s pulp and paper market and consolidate its technological advantages in the field of intelligent chemical recovery analysis. It also lays a solid foundation for long-term in-depth cooperation between the two sides. Recognizing the outstanding application performance of the Nanning base project, Sun Paper Group placed additional orders for two sets of Valmet Alkali R for its Beihai and Yandian bases in January 2026, fully demonstrating high recognition of Valmet’s product technology and one-stop service.

As a benchmark enterprise in China’s chemical pulp industry, Sun Paper Group has built a global industrial layout with coordinated development of three major production bases in Shandong, Guangxi, and Laos, ranking among China’s Top 500 Enterprises. Located in Liujing Industrial Park of Nanning, Nanning Sun Paper is a core strategic base of Sun Paper’s integrated forest-paper-industry layout and a key leading enterprise driving Nanning’s industrial development. It continuously empowers and boosts the upgrading of the regional paper industrial cluster.