The fact that the raw water was regularly mixed with return condensate was a significant complication in this plant. The feed conductivity ranged between < 50 and > 500 µS/cm!
Looking back, we can proudly say: We had been waiting for such a challenge! For it is only under such extreme conditions that the relief provided by Mi‑Vision becomes really visible: despite extremely fluctuating feeds, it can map and evaluate the loadings well. The HCO3-, FMA and TDS contents measured in real time by Mi‑Vision are shown in the following graph as an example.
The operator already had +m and -m titrators in his plant and thus some basic principles of Mi‑Vision already installed in terms of analysis.
It became apparent very soon that the precision and speed of the Mi‑Vision results were superior to even these +m- and -m-value online titrators in operating conditions with very rapid changes:
With the permanent installation of the new Mi‑Vision system, the titrators have now been decommissioned.
Reliable SiO2-measurement by Mi‑Vision even for highly fluctuating feeds
During the evaluation phase, the line was conducted in a controlled manner until a breakthrough occurred - either caused by the cation or the anion exchanger in order to achieve a more cost-effective operation than the existing one.
The picture illustrates the typically very good correspondence between the built-in online silicometer (red) and the Mi‑Vision measurement (green):
Significant cost reduction already during the test phase
We monitored a line that had set the conductivity breakthrough after the weakly basic stage (WBA) as a termination criterion. The regenerant excesses were extremely high due to short loadings (approx. 300 % for SAC and 200 % for WBA despite a compound on the AN side).
The graph shows the values of the regenerant excess (RE) of many runs. In fact, the RE is the most important operating cost indicator.
The left half of the diagram shows the old operating pattern until May 2020. From July, the line was regularly conducted until SiO2 breakthrough became apparent. As the resins are quite old, the AN side was always causing the breakthrough over SiO2.
On the right half of the diagram, the plant operators have adjusted the quantities of regenerant in the DCS according to the suggestions by Mi‑Vision. Thus, the line was operated with constant RE. Essentially, the two curves for acid and caustic RE approach straight lines whose levels are roughly half of the old ones.
Since RE = chemical costs, a regenerant saving of about 40 % could be achieved at this plant thanks to Mi‑Vision!