CAUST-X: The active lime dosage is controlled to produce white liquor required for cooking the wood chip.

CAUST-X is an advanced process control solution developed in partnership with FPInnovations.  CAUST-X is deployed under license directly within the mill DCS.

CAUST-X is a mechanistic model that delivers the production of strong white liquor and helps prevent green liquor crystallization, over-liming and weak white liquor. We cover the application from simple conductivity measurements, titration based measurements or NIR based sensors.  CAUST-X is deployed either directly into the mill DCS or through OPC (Ole for Process Control).


CAUST-X consists of several modules: SMELT for raw green liquor TTA control, CGL TTA for clarified green liquor, LQE lime quality estimator with CE soft sensors at causticizers, LIME for reburnt and fresh lime dosage to slaker, and TEMP for slaker temperature control.

• CAUST-X SMELT stabilizes TTA from smelt dissolving tank using our proprietary TTA soft sensor which uses TTA measurement from lab test or automatic online analyzer like FT-NIR along with online density measurement to provide a continuous reliable TTA measurement to controller. It also provides automatic TTA setpoint to prevent pirssonite deposit from TTA/GL Temperature fluctuation. 
• CAUST-X CGL TTA controller stabilizes CGL TTA going into slaker using our proprietary TTA soft sensor which uses TTA measurement from lab test or automatic online analyzer like FT-NIR along with online density measurement to provide a continuous reliable TTA measurement to controller.
• CAUST-X Slaker temperature controller to prevent slaker boil out by controlling GL temperature controller
• CAUST-X CEss soft sensors provides continuous CE measurement using our proprietary CE soft sensor which uses CE measurement from lab test or automatic online analyzer like FT-NIR along with online conductivity measurement
• CAUST-X LQE Lime Quality Estimator uses the measurement and feedback from all aforementioned sensors and instruments to estimate the lime quality and therefore optimize the lime dosage to achieve operator desired final WL CE.
  

OBJECTIVES for CAUST-X are:

• Control and predict the causticizing reaction efficiency
• Achieve tight control of the chemical feeds to optimize and stabilize white liquor composition.
• Control the slaker operation by optimizing CE and temperature.
• Respond to disturbances and maintain operating stability over a wide range of conditions
• Reduced system training as CAUST-X is deployed directly onto the mill DCS by the mill E&I technicians.

FEATURES

• Prevents over-liming as dosage is controlled by the CAUST-X based on the system information
• Control algorithms implemented under license in any DCS
• Extensive documentation provided
• Custom DCS interface integrated to existing operator interface;
• On-the-job operator training with experienced process control engineer.

REQUIREMENTS

• Density measurement  for RGL in smelt dissolving tank and CGL before slaker
• Temperature measurement of CGL and slaker
• Lime feed screw motor speed
• Conductivity measurement in causticizers

BENEFITS

• Reduced TTA variability (up to 30%)
• Improved slaker operation
• Increase of CE (typical 1%)
• Reduced over-liming instances
• Reduced EA variability (up to 40%)
• Improved process stability
• Reduced manual control actions

White papers
Kinetic Model-Based State Estimation and Inferential Control of the Causticizing Process

Causticising reaction kinetics