In a measurement and control system, the analytical side always comes first, i.e. the diagnosis of the feed. Based on this, Mi‑Vision then simulates the behaviour of your DI-line in real time.
Mi‑Vision uses the quotient of the conductivities before and after the cation exchanger. This method provides the three decisive parameters (cations, mineral acid anions and HCO3-) very precisely in real time, even taking variable dilutions into account, e.g. due to the addition of condensate or seasonal variations in the water analysis. Furthermore, influences of e.g. an upstream lime decarbonisation or an acidic feed are fully included.
The three mentioned values as well as SiO2 and the leakage of the degasser are sufficient for determining the loading of the four individual stages in the DI-line. In the meantime, the degasser leakage is determined automatically by Mi‑Vision even for degassers between CAT and AN. You will never need to titrate it again!
The next essential step is the simulation of breakthrough curves. With the help of these curves, the expected concentration of the individual components of the water analysis can then be calculated after each individual resin stage as a function of the loading progress.
A total of 5 individual breakthrough curves are provided in the Mi‑Vision system, as the weak-base stage clearly distinguishes between a HCO3- and a FMA breakthrough. This very high level of detail led to surprisingly good correspondences between simulated and measured concentration curves.
The sections of the water analysis taken up by each individual stage are then added up to the loading of each individual stage. Resulting in the display of 4 "thermometer columns" representing the loadings of each stage.
At the end of loading, the quantity of regenerant required is calculated based on the achieved loads - multiplied with a necessary excess. Through feedback into your DCS, this value can be used for dynamic adjustment of the quantity of regenerant. This achieves the goal, which has been strived for over many years, that your DI-plant can also always be operated with a constant surplus and thus with constantly low chemical costs.
