UPA | On-line monitoring of black, white and green liquor

On-line monitoring of pulping liquor

Pulp & Paper industry

Kraft (or sulfate) pulping processes comprise the majority of all pulping processes used worldwide. The kraft process is essentially a sodium-based alkaline pulping solution (liquor) consisting of sodium sulfide (Na2S) and sodium hydroxide (NaOH). Recovery of pulping chemicals, obtained by the causticizing process, is a conditio sine qua non for efficient production, and should be as high as possible.

On-line monitoring of the pulping liquors is the key to efficient caustizing, reduced emissions and reduced give-aways. The white liquor (the fresh pulping liquor), black liquor (spent pulping liquor) and green liquor (recovered liquor) can be analyzed continuously (batch) in a typcial titration sequence, sometimes also referred to as "ABC analysis". Measurements are carried out by one and the same titrimetric process analyzer, through a multiplexed sample preconditioning unit.

Feasible parameters

NaOH, Na2S, Na2CO3

Calculation of Effective, Active and Total Alkali

Sample preconditioning

The pulping process, either chemical, mechanical, or waste-paper pulping, requires purpose-built analyzer equipment to cope with the harsh environment present. AppliTek designs a specific preconditioning for sampling the pulping liquors, with the necessary provisions for extreme temperatures, pressures, viscosity... For more information, please check the following section:

» Go to  System integration / Sample preconditioning