The Dissolving Tank Analyzer

The Dissolving Liquor Analyzer solution is a reliable and accurate liquor analysis at the dissolving tank and stabilization tank locations. The solution allows the ability to control the quality of the green liquor that is pumped to the causticizing process. Stabilizing the green liquor composition at these locations ensures that variations in the green liquor are minimized before reaching the recaustizing area.
Stabilization of the green liquor at the dissolving tank is also important for controlling the settling characteristics of the liquor and minimizing scale buildup in the piping and process equipment. It is desirable to maintain green liquor TTA in as tight a range as possible; too high of a TTA can lead to scaling issues while too low pf a TTA leads to reactivity issues at the slaker. With an online dissolving/stabilization tank analyzer, the green liquor composition can be controlled in real time to meet target TTA or Na2CO3 levels.
In addition to the green liquor analysis provided by this analyzer, weak wash TTA is also provided allowing for a feed forward-feedback control arrangement. The DURALYZER-NIR dissolving/stabilization tank analyzer provides the required green liquor AA and TTA measurements in a timely, accurate and reliable manner for green liquor composition control. Plus, green liquor EA, TDS and TDD are also available from the same analyzer as well as the weak wash TTA measurement.
Another important measurement of the Dissolving Tank Analyzer is Reduction Efficiency measurement RE%=Na2S/(Na2S+Na2SO4). This can be used as a feedback signal for controlling air flows of the Recovery Boiler.
Application Technology
Reliable and accurate green liquor analysis for the Dissolving tank process is important for optimizing TTA or Na2CO3 levels. The above graph shows how the DURALYZER-NIR dissolving/stabilization tank analyzer can be implemented for controlling the composition of the green liquor exiting these tanks. The standard analyzer configuration comes with three sample lines. A control signal based on green liquor TTA or Na2CO3 levels can then be used to adjust weak wash flow to maintain target TTA or Na2CO3 levels.
The combination green liquor analysis and weak wash analysis from the analyzer can be used for the stabilization tanks to get tight control over the green liquor composition using a feedforward-feedback control system. The dissolving tank analysis is unique among the liquor analysis applications due to the rapid step changes that can occur from smelt rush conditions. In addition, scaling at this location can also be a serious issue, quickly fouling other sensor solutions to a degree that makes them inoperable.
The DURALYZER-NIR analyzer solves both of these issues. Green liquor analysis results can be provided in as short  as a three minute cycle. Special Teflon lined sample taps ensure that the tap locations do not scale up to a degree that would interfere with collecting a valid process sample.

​Manufactured by: R.E. Hodges, Alabama, USA