Metris Kiln ACE is an advanced process control system for lime kilns in kraft pulp mills. Using BrainWave® MPC, it maximizes lime throughput and quality, minimizes fuel consumption, and eliminates the need for high-temperature operating margins that waste energy and accelerate refractory wear.
Metris Kiln ACE is a control optimization system for lime kilns in the kraft pulp mill chemical recovery cycle. Using BrainWave® Model Predictive Control (MPC), Kiln ACE manages the slow, non-linear thermal dynamics of the rotary lime kiln to keep costs as low as possible while continuously delivering reburned lime that meets quality specifications.
Lime kilns are among the largest energy consumers in a kraft pulp mill, and their long thermal response times — often several hours — make stable manual operation extremely challenging. Disturbances from changing production rates, varying mud solids content, and NCG waste gas firing compound the difficulty. To compensate, operators typically run kilns at elevated temperatures and high excess oxygen to avoid under-burned lime or emissions violations. These practices increase fuel consumption, accelerate refractory wear, promote ring formation, and degrade lime quality.
Kiln ACE replaces this conservative margin-based approach with model predictive control that manages temperature profile, fuel mix, and excess oxygen simultaneously. Multi-fuel support is provided through two dedicated function blocks: the Specific Energy Calculation block adjusts each fuel flow based on its low heating value (LHV) to deliver the required power regardless of fuel mix; the Stoichiometric Air Calculation block adjusts primary airflow based on fuel-specific air demand to maintain stable combustion and flame quality independent of fuel combination changes.
The Kiln Inventory Management block smoothly handles production rate changes — the largest process disturbance — by managing mud tank and lime bin levels while coordinating the production rate adjustment. The Residual Carbonate Control block adjusts feed end and hot end temperature set points to ensure uniform heat distribution across the kiln, optimal lime quality, and reduced ring formation risk. DCS interface: 50 I/O data exchange configurations, 3 control loop interfaces, and 1 dedicated DCS display for limit and target setting (or Metris All-in-one Platform as operator station).
Kiln ACE is a component of the Autonomous Kiln solution.
