33% More Chlorides Removed. 69% Higher Equipment Availability. No Equipment Upgrade Required.
33% More Chlorides Removed. 69% Higher Equipment Availability. No Equipment Upgrade Required.
Unlocking CRP Performance Without an Equipment Upgrade
The chloride removal plant (CRP) at a pulp mill was struggling to remove sufficient chlorides from recovery boiler ash. The resulting chloride build-up contributed to sticky fouling within the recovery boiler, creating operational constraints and raising concerns about future production capacity. The mill was considering a costly upgrade and replacement of the CRP to address the problem.
At the same time, the CRP suffered from significant reliability challenges. Critical process areas relied heavily on manual intervention, leading to unstable feed conditions, inconsistent salt cake density, excessive centrifuge vibration, plant shutdowns, and reduced chloride removal performance.
Anssum implemented advanced process control and automation strategies across the existing plant infrastructure. Without any plant modifications or additional instrumentation, chloride removal increased by 33%, centrifuge availability improved by 68%, and overall ash processing increased by 19%, eliminating the need for a major capital upgrade.
Recovery Chemical Management at a Large Pulp Mill
A large integrated pulp mill where recovery boiler performance is critical to overall mill production and energy efficiency.
The chloride removal plant plays an important role in maintaining the recovery cycle by removing chlorides and potassium from recovery boiler ash before it is returned to the process. Effective operation of the CRP is essential for minimising fouling, maintaining boiler reliability, and supporting long-term production performance.
Poor Chloride Removal Constrains Recovery Boiler Performance
The CRP relied heavily on manual operation across several critical process areas, including feed density stabilisation, crystallisation control, and centrifuge operation.
This resulted in:
- Inconsistent feed quality entering the centrifuge.
- High centrifuge vibration levels and reliability issues.
- Frequent operational interventions and plant shutdowns.
- Reduced chloride and potassium removal efficiency.
- Variable throughput and process instability.
- Sticky fouling in the recovery boiler caused by elevated chloride levels.
- Consideration of a costly CRP upgrade to address performance limitations.
They believed additional equipment capacity is required to achieve the targeted chloride removal.
Improving CRP Performance Through Process Control
Rather than proceeding directly to a capital-intensive plant upgrade, Anssum focused on addressing the underlying operating and control limitations within the existing CRP.
The solution includes:
- Automated feed density stabilisation.
- Advanced control of crystalliser operation.
- Real-time monitoring and control of critical process variables.
- Improved centrifuge control to reduce vibration.
- Automated control responses to changing process conditions.
- Improved coordination between upstream and downstream process units.
- Integration into the existing control system without requiring additional instrumentation.
The objective was to improve chloride removal performance, increase centrifuge reliability, and stabilise plant operation while maintaining operator ownership of the process.
Implementation Process
Understand the Operational Constraint
- Analysis of historical CRP performance and operating behaviour.
- Identification of sources of process variability affecting chloride removal and centrifuge performance.
- Evaluation of the relationship between feed conditions, salt cake density, vibration, and plant reliability.
- Quantification of the operational and financial impact of current performance limitations.
This established a clear view of the underlying performance restrictions and ensured the solution addressed root causes rather than symptoms.
Develop the Solution with the Mill Team
- Collaborative solution development involving operations personnel, engineers, and control specialists.
- Incorporation of operator experience into the control philosophy.
- Definition of operating targets, safeguards, and performance objectives.
- Evaluation of implementation strategies to minimise operational risk.
This ensured the solution remained practical for the plant team and supported long-term adoption.
Implement Within the Existing Control Environment
- Integration of improved control strategies into the existing control system.
- Automation of critical functions previously dependent on manual intervention.
- Improved coordination between process units.
- Implementation without plant modifications or additional instrumentation.
Implementation was completed within systems already familiar to operators and maintenance personnel.
Commission and Refine
- Commissioning alongside plant personnel.
- Progressive refinement of density control, crystallisation performance, and centrifuge operation.
- Reduction of process variability and vibration levels.
- Verification of improvements in throughput, reliability, and chloride removal efficiency.
Embed and Transfer Ownership
- Training of operators and technical personnel.
- Integration of the solution into normal operating practices.
- Establishment of performance monitoring processes.
Transfer of day-to-day ownership to the mill team to support sustained performance and continuous improvement.
Improved CRP Performance Without an Equipment Upgrade
The improved control approach increased both process performance and plant reliability.
Key outcomes included:
- 33% increase in chlorides removed.
- 21% reduction in boiler ash chlorides.
- 12% increase in mill-wide chloride ratio.
- 68% increase in centrifuge availability.
- 48% increase in centrifuge load.
- 93% reduction in mix tank over-dilution.
- 19% increase in ash processed.
Key Takeaways
Control Problems Often Resemble Equipment Limitations
The perceived capacity constraint was resolved through improved control rather than equipment replacement.
Stability Improves Performance and Reliability
Reducing process variability increased chloride removal, throughput and centrifuge availability.
Improved Control Avoids Capital Expenditure
The improvements required no additional instrumentation or plant modifications.
Operator Involvement Sustains Results
Close collaboration with plant personnel supported adoption and long-term ownership.
