21.2.2 Solution Strategies

To solve for SOx products:

• (optional) If the discrete phase model (DPM) is activated (by turning on the Interaction with Continuous Phase) to run with the SOx model, then set the Number of Continuous Phase Iterations per DPM Iteration to 0 such that no DPM iterations are performed as the SOx case is being solved.

• In the Equations dialog box, turn off the solution of all variables except Pollutant so2 and Pollutant h2s (and Pollutant so3, Pollutant sh, and Pollutant so, if applicable).

  Solution Controls Equations...

• Also in the Solution Controls task page, set suitable values for the pollutant SO $_2$ and H $_2$S (and SO $_3$, SH, and SO, if applicable) under-relaxation factors. A value of 0.95 is suggested, although lower values may be required for certain problems. That is, if convergence cannot be obtained, try a lower under-relaxation value.

  Solution Controls

• Under Spatial Discretization, in the Solution Methods task page select the desired scheme for each of the pollutants,SO $_2$ and H $_2$S (and SO $_3$, SH, and SO, if applicable)

  Solution Methods

• In the Residual Monitors dialog box, decrease the convergence criterion for the pollutants, SO $_2$ and H $_2$S (and SO $_3$, SH, and SO, if applicable) to $10^{-6}$.

  Solve $\rightarrow$ Monitors $\rightarrow$ Residual...

• Perform calculations until convergence (i.e., until the SO $_2$ and H $_2$S (and SO $_3$, SH, and SO) pollutant residuals are below $10^{-6}$) to ensure that the SO $_2$ and H $_2$S (and SO $_3$, SH, and SO) concentration fields are no longer evolving.

• Review the mass fractions of pollutants, SO $_2$ and H $_2$S (and SO $_3$, SH, and SO) alphanumerics and/or graphics tools as described in Section  21.2.3.