The encyclopedia · Engineering & Operations · Technical decision · 2000–2007
Billerud's OptCab re-solves bleaching chemistry every five minutes, cutting chemicals 10%
Billerud let an online optimizer run pulp bleaching: models refresh every 15 minutes, the mix re-solves every five — 10% fewer chemicals.
Billerud
The solution
Billerud's Skärblacka mill in Sweden bleaches pulp to a target brightness, dosing chemicals through sequential stages. Raw material — pulp logs and wood chips — varies in quality, so the right dosage changes constantly; operators traditionally set it by experience.
With Linköping University and Eurocon Automation, the mill built OptCab: every 15 minutes it re-estimates each stage's model from process data, and every five minutes it solves a linked nonlinear control problem minimizing chemical cost while holding brightness.
Fully operational since 2004, OptCab cut chemical use by about 10 percent — roughly €2 million saved since installation — while making brightness more stable and freeing operators for development and analysis work.
Why it worked
- Models tracked a drifting process instead of assuming a fixed recipe
- Re-solving every five minutes kept the plant near its optimum
- Brightness held within limits, so quality stayed consistent
- Chemical savings fell straight to the mill's variable-cost line
What can be applied
For a process whose inputs drift constantly, static recipes waste chemicals: online optimization that re-estimates the process and re-solves control pays for itself in consumables and quality.
Aftermath
Eurocon commercialized OptCab as a general tool for bleaching control, and Billerud's case became a reference for online optimization in the process industry.
Sources
- Billerud Optimizes Its Bleaching Process Using Online Optimization
- Optimized On-Line Process Control of Bleaching Operations with OptCab
spotted an error? The archive wants to know.