Computes the excess air percentage for both current and improved conditions based on measured flue gas oxygen and process-specific multipliers. Excess air is a key indicator of combustion efficiency and impacts fuel usage.

\begin{equation}\label{eq:pheic-excess-air} EA = \frac{100 \cdot S_A \cdot (\frac{O_2}{100})}{D_B - O_2M \cdot (\frac{O_2}{100})}\end{equation}

\(EA\)	Excess air \([\unit{ \percent}]\)
\(S_A\)	Stoichiometric air multiplier (8.52381) \([\unit{ \unitless}]\)
\(O_2\)	Flue gas oxygen (dry) \([\unit{ \percent}]\)
\(D_B\)	Denominator base (2.0) \([\unit{ \unitless}]\)
\(O_2M\)	O2 denominator multiplier (9.52381) \([\unit{ \unitless}]\)