Digital Divert Control System for Safe Operation of Recovery Boilers in Industrial Mills
In the pulp and paper industry, firing of black liquor in recovery boilers present a high-stakes industrial hazard, which necessitates administration by skilled and trained operators, along with the use of suitable instrumentation and automation systems.
The process of firing black liquor safely can now be addressed with the recent addition to Vaisala’s Polaris range – the Digital Divert Control System DD53.
All components of this control solution are available at ADM Instrumentation Engineering, with our local experts on standby should you need to discuss your application.
Features of the Vaisala Polaris Digital Divert Control System
To implement a fully digital control solution for black liquor concentration and safe firing, the following products are combined:
Two to three Vaisala Polaris PR53SD process refractometers,
Two or three Indigo520 indicating transmitters, and
One DD53 digital divert control unit.
Vaisala Polaris PR53SD process refractometers provide continuous, inline measurement of black liquor solids concentration. This device’s Safe-Drive feature allows the refractometer to be safely inserted or removed from pressurised black liquor piping without shutting down the operation.
The Indigo520 transmitters, on the other hand, provide a central interface for diagnostics, wash control, data logging, and secure connectivity, to allow reliable integration of the refractometer into the mill control system.
Lastly, the DD53 digital divert control unit is a microprocessor-controlled, SIL-rated (Safety Integrated Level) digital divert unit with redundant power supplies and built-in diagnostics for dependable divert operation and direct integration with control and burner management systems.
Benefits of the Vaisala Polaris Digital Divert Control System DD53
The Vaisala Polaris DD53 Digital Divert Control System provides a modern, fully digital approach to safe black liquor firing, combining BLRBAC-compliant divert control with 2-out-of-3 refractometer logic for safety and process reliability. It can be integrated with existing PR-23 and DTR installations and connects directly to mill control systems and the Burner Management System (BMS) through industry-standard communication interfaces. Digital signal transmission, microprocessor-based diagnostics, SIL-rated critical components, and redundant power supplies further support fail-safe operation.
