OPT800 Lime

ABB AbilityTM Advanced Process Control for stabilized and optimized lime production in a pulp mill

OPT800 Lime results in uniform lime quality with low energy consumption and reduced emissions. The Advanced Process Control solution analyzes residual carbonates during laboratory tests to optimize control targets and ultimately produce lime efficiently and economically.

The lime kiln operation in the kraft pulping recovery process, though straightforward in principle, can be challenging to operate at high efficiency. Some of the difficult issues faced by kiln operators include low thermal efficiency, high fuel consumption, process delays, build-up of rings and dust, overheating of refractory, poor quality of lime and increased emissions.

OPT800 Lime manages these challenges to achieve optimum control and efficient lime production. The program works to optimize lime production rates; reduce energy consumption and emissions; increase re-burned lime availability; decrease residual carbonate variations; and improve the overall mill operation with increased visibility over the process. It combines laboratory results by operators with model-based predictive control, thus getting the best of both approaches in a fully product-specific solution, with minimum need for on-site development.

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  • Production rate control
  • Burning Zone Temperature control
  • Draft control Residual carbonate control
  • Control usage reports
  • Real-time adaptive modelling: Automatic adjustments based on process changes
  • Higher-order model support: Captures process dynamics accurately
  • Cost optimizer: Looks for ways to optimize operational costs within process constraints
  • KPI Dashboard and control usage reports by day/shift
  • Performance monitoring, with both on-site and remote access for customer and ABB
  • Task oriented and user friendly customizable operator displays


  • Increased production rate
  • Reduced energy consumption by up to 8%
  • Reduced excess oxygen variation by up to 60%
  • Reduced lime quality variation
  • Reduced fuel consumption
  • Improved re-burned lime quality

How it works – Getting best lime quality and production rates

The OPT800 Lime system introduces frequent but small adjustments within the operational limits to obtain continuous optimization, thereby reducing the process variance and improving the overall mill performance. The adjustments are made by controlling the temperature profile, flue gas emissions, lime mud flow and residual carbonates of the refractory. At its core, the system utilizes a model of the kiln process to accurately predict process variable interactions. These lead to smooth and stable mill operation and uniform lime quality. Control performance will not degrade over time with always-on monitoring and analysis of the APC solution.
  • Lime kiln controls include temperature profile, excess oxygen, mud feed, mud density and fuel flow control. These are used to manage the temperature profile while maintaining re-burned lime quality at optimal levels. This, in turn, extends lime refractory life due to more stable operations and low temperature fluctuations.
  • Production Rate Control accounts for the process dynamics and coordinates the ramping of various operating parameters such as the lime mud flow, lime mud density, fuel flow, etc. to ensure minimal quality variation and off-spec lime during production rate changes.
  • Residual Carbonate Control is an optional feature of OPT800 Lime to maintain the optimal levels of residual carbonate. Residual carbonates are measured with the help of laboratory analysis and the system monitors long term trends of laboratory test results to provide optimized control targets.
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