Evaporation plant at Ružomberok

ANDRITZ Liquor Heat Treatment (LHT) system

One of the challenges of evaporating water from black liquor is that the physical properties of black liquor change significantly when it is concentrated.  Concentrated black liquor has high viscosity, which can cause significant problems with plugging of equipment.  ANDRITZ has developed a simple yet effective treatment technology for black liquor that permanently reduces the viscosity of high dry solids liquors so that they can be efficiently burned in the chemical recovery boiler. 

LHT process schematic

Higher dry solids generates more energy

Modern mills rely on very high final dry solids liquor from the evaporation process in order to extract maximum energy efficiency from the chemical recovery boiler.  Depending upon the chemical composition of the liquor, the viscosity of the liquor as it is being concentrated increases to such a level that makes further liquor processing difficult, as the highly viscous liquor plugs the process equipment.

In the ANDRITZ Liquor Heat Treatment (LHT) system, the liquor is processed at elevated temperatures which permanently reduces the liquor viscosity so that it can be stored, transported, and combusted at higher dry solids levels.

ANDRITZ LHT applications

  • Kraft liquor
  • Soda liquor
  • NSSC liquor

High energy efficiency

An LHT system and process can be easily integrated into multiple-effect evaporators and concentrators – or can be operated as a standalone system.  The system is engineered and designed for maximum energy efficiency with heat sources integrated into existing processes.

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