In addition to advanced process solutions, Valmet also provides built-in intelligence for each fiber line process unit. These APC (Advanced Process Control) systems help customers reach production and quality targets quicker and with minor risks.
The control system analyzes information from various stages of the fiber line and helps operators optimize the process parameters.
The control of a digester plant is divided into two major areas:
1. Basic control functions normally performed in a DCS (Distributed Control System), which consist of single loops, safety interlocks, automatic sequences, and recipe management and pulp quality control.
2. Supervisory control functions, assembled in a complete program package called APC cooking.
The APC system handles advanced control and planning functions, such as:
- Digester/liquor line scheduling with production control
- Tank farm control R
- escheduling of sequences
- Steam leveling
Pulp washing, delignification and bleaching
Due to ever increasing demands for process closure, the need for an intelligent operation control of a fiber line has become vital. This concerns mainly production and liquor balance functions, as well as chemical charges in varying operating conditions.
APC control in delignification and bleaching stages results in fewer variations in pulp quality, higher pulp quality and optimized chemical charges. Variations in outlet kappa, brightness and final pH are considerably reduced, using this control strategy. Implementing a control strategy results in lower chemical costs and a reduced amount of inferior pulp. This control strategy also simplifies decision support for operators.