Evaporator Capacity & Solids Control
Evaporator Capacity & Solids Control
10X Value to Cost Ratio
We embedded a viscosity-based soft sensor and model-predictive control (MPC) on a seven-effect evaporator train. The retrofit released 2.8 L/s of extra hydraulic capacity, stabilised liquor-solids, and removed almost every unplanned drain-and-wash event. Finance verified recurring savings represent a value-to-cost ratio well above 10 : 1.
650,000 ton per Year Bleached Kraft Pulp Mill
For nearly five decades this coastal kraft complex has converted sustainably managed eucalyptus into ≈ 650,000 t of bleached pulp per year, supplying packaging customers acrossAfrica, Europe and the Middle East. Its seven-effect evaporator set is the sole feed to the recovery boiler and a primary production bottleneck.
Liquor-Solids Variability & Drain Downtime
When we started working with this client, they were facing numerous challenges
- Elevated energy prices – national steam costs > 40 % above 2019 levels.
- Stringent water-use permits – every liquor drain must be neutralised under strict discharge limits.
- Fibre-cost inflation – hardwood index ≈ 27 % higher than its pre-pandemic baseline.
Manual density control and fixed wash intervals triggered frequent off-spec liquor and drainage events, wasting steam and chemicals while throttling black-liquor throughput.
Some of their key pain points were
- 10–12 unplanned drains per month, each costing steam and chemicals.
- Steam-economy drift ± 3 %.
- Solids excursions upset downstream boiler efficiency.
Anssum's Three Step Solution Framework
Considering the many challenges the client's mill was facing, we knew that we needed a focused approach. Our solution was therefore centered around Anssum's three step solution framework:
- Data driven discovery
- Collaborative design
- Straightforward integration
Implementation Process
€ 395,000 Annual Gain
Financial Summary – value-to-cost ratio > 10 ×, payback in under 3 months.
Key Takeaways
Soft sensors reveal hidden capacity — near-lab accuracy without new instrumentation.
Wash-on-need beats fixed intervals — cleaning only when fouling cost outweighs steam cost.
Energy & Water wins align with ESG — less steam and fewer drains cutCO₂ and effluent load.
Operator co-design secures adoption — front-line teams own the thresholds they trust.
