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Journal articles
Energy and emission implications of optimized white liquor causticity, TAPPI Journal January 2026
ABSTRACT: Optimizing the causticizing plant offers significant opportunities for energy and emissions savings in kraft mills by minimizing the chemical and water deadload introduced into the recovery cycle via white liquor. Modern control strategies utilize both feedforward and feedback loops to manage causticity, enabling more aggressive targets closer to equilibrium levels. This paper evaluates the benefits of optimizing white liquor chemistry through a detailed CADSIM Plus simulation model, replicating the chemistry of a Canadian bleached kraft mill that adopted an automated causticizing control system. The control system increased causticity from 77.0% to 82.3% at a fixed total titratable alkali (TTA) of 126.5 grams of sodium dioxide per liter (gNa2O/L). Modeling this chemistry change indicated a 1.5 metric tons per hour (t/hr) reduction in evaporator steam demand and a 2.8% increase in black liquor higher heating value. Consequently, the improved heating value resulted in a 1.5% rise in recovery boiler steam production and a 5.3% reduction in biomass energy consumption in power boilers, leading to a 4.8% decrease in biogenic carbon dioxide (CO2) emissions. Additionally, reducing the inorganic and water deadload throughout the recovery cycle may support higher as-fired dry solids targets, enhancing recovery boiler energy efficiency by lowering the water evaporation requirement during black liquor combustion. However, implementing a causticizing control system requires careful assessment of potential lime kiln bottlenecks, as increased causticity demands may affect kiln operations depending on broader mill conditions. Overall, an automated causticizing control system enhances process efficiency, reduces energy consumption and emissions, and positions kraft mills for improved productivity and longterm sustainability.
Journal articles
Effects of variability of wood chip composition on recovery cycle operation, TAPPI Journal January 2026
ABSTRACT: Fluctuations in wood chip properties in kraft pulp mills, which often follow seasonal patterns, can lead to changes or disruptions in the operation of the recovery cycle whereby the root causes are not immediately obvious. In some cases, these changes are attributed to operational adjustments in the digester or brownstock washing areas resulting from the variability in wood characteristics. Varying wood chip characteristics that have the most significant impact on the recovery cycle operation include the content of non-process elements (NPEs), extractives, and properties influenced by chip storage conditions. Elevated levels of NPEs, often associated with a higher influx of wood bark into the digester, can negatively affect the entire recovery cycle. Increased levels of chlorine and potassium can lead to severe fouling and corrosion in the recovery boiler. Higher concentrations of silicon, aluminum, phosphorus, magnesium and calcium in the chips may accelerate scaling in the evaporation plant, impair dregs and lime mud settling and filtering, reduce lime mud solids content and lime availability, and increase the amounts of dregs, grits, and purged lime mud. This technical review provides an overview of the most significant effects that changes in wood chip quality can potentially exert on various processes within the kraft recovery cycle.
Journal articles
Development and Application of a Real-Time Recovery Boiler E
Development and Application of a Real-Time Recovery Boiler Expert System, 1991 Engineering Conference Proceedings
Journal articles
Recovery of Sulfur from Spent Semichemical Pulping Liquors,
Recovery of Sulfur from Spent Semichemical Pulping Liquors, 1991 Engineering Conference Proceedings
Journal articles
Development and validation of an improved drainage testing, TAPPI JOURNAL, April 2000, Vol. 83(4)
Development and validation of an improved drainage testing, TAPPI JOURNAL, April 2000, Vol. 83(4)
Journal articles
High temperature chlorine dioxide bleaching of hardwood kraft pulp, TAPPI JOURNAL, August 2000, Vol. 83(8)
High temperature chlorine dioxide bleaching of hardwood kraft pulp, TAPPI JOURNAL, August 2000, Vol. 83(8)
Journal articles
An engineered approach to paper and print improvement, TAPPI JOURNAL, December 2000, Vol. 83(12)
An engineered approach to paper and print improvement, TAPPI JOURNAL, December 2000, Vol. 83(12)
Journal articles
Direct causticization of kraft black liquor solids with tio2 in a fluidized bed, TAPPI JOURNAL, December 2000, Vol. 83(12)
Direct causticization of kraft black liquor solids with tio2 in a fluidized bed, TAPPI JOURNAL, December 2000, Vol. 83(12)
Journal articles
Pulping of aspen wood in acetic acid media: effect of operating conditions on yield and pulp properties, TAPPI JOURNAL, December 2000, Vol. 83(12)
Pulping of aspen wood in acetic acid media: effect of operating conditions on yield and pulp properties, TAPPI JOURNAL, December 2000, Vol. 83(12)
Journal articles
Wood quality ranking of plantation trees, TAPPI JOURNAL, December 2000, Vol. 83(12)
Wood quality ranking of plantation trees, TAPPI JOURNAL, December 2000, Vol. 83(12)