# Flue Gas Composition and Treatment Potential of a Waste Incineration Plant
## 3 Results
### Flue Gas Density Effect (Checked by Epsilon)  
The effect of flue gas density is important for the specification of the amount of CO\({}_{2}\) emissions. It is well-known that the density of flue gas decreases with increases in its temperature, which leads to an increase in CO\({}_{2}\) emissions (see Figure 5). This has a direct  
Figure 4: Results of CO\({}_{2}\), O\({}_{2}\), and air mass flow obtained from the calculation model.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{3}{*}{\begin{tabular}{c} **Excess Air** \\ **(A)** \\ \end{tabular} } & \multirow{3}{*}{\
\begin{tabular}{c} **MSW Mass** \\ **Flow (kg/s)** \\ \end{tabular} } & \multicolumn{3}{c}{**Calculated**} & \multirow{3}{*}{**Model Calculations**} & \multicolumn{3}{c}{**Epsilon Results**} \\  & & & **Volumetric** & & & & & **Air Mass** \\  & & **Flow (kg/s)** & & & & & & **Flow (kg/s)** \\ \hline \hline \multirow{3}{*}{
\begin{tabular}{c} 1.5 \\ 2 \\ 2.5 \\ 2.5 \\ 30 \\ \end{tabular} } & 25 & 2.55 & 5 & 15 & 54 & 5.4 & 14.4 & 51.5 \\  & 25 & 2.67 & 8 & 12 & 69.4 & 8.8 & 11.6 & 68.7 \\  & 25 & 2.78 & 12 & 8 & 86 & 11.2 & 9.7 & 85.8 \\  & 30 & 2.55 & 5 & 15 & 62.4 & 5.4 & 14.4 & 61.8 \\  & 30 & 2.67 & 8 & 12 & 83.3 & 8.8 & 11.6 & 82.4 \\  & 30 & 2.78 & 12 & 9 & 104 & 11.2 & 9.8 & 103 \\ \hline \hline \end{tabular}
\end{table}
Table 10: Volumes of O\({}_{2}\) and CO\({}_{2}\) in flue gas and the air mass flow required in the furnace (verified using the model calculation and Epsilon simulation).  
effect on the air ratio (excess air/stoichiometric air) in the combustion chamber (furnace), where the emissions decrease when the air ratio is increased. It can be said for any waste incineration process that working at 800 \({}^{\circ}\)C is better than working at 1000 \({}^{\circ}\)C in terms of emissions, specifically CO2 emissions; on the other hand, it is preferable to work with higher temperatures in terms of energy.  
The results showed that when the temperature of the flue gas was around 70 \({}^{\circ}\)C, its density was 1.3 kg/m\({}^{3}\), while the CO2 emissions were at a minimum value of 77 kg/s. On the other hand, when the flue gas temperature reached 1200 \({}^{\circ}\)C, the density was 0.24 kg/m\({}^{3}\) and the CO2 emission was at 203 kg/s.  
Figure 6 is a theoretical illustration of how when the air ratio was increased to 8, the CO2 emissions reached their lowest value of 77 kg/s, and the highest of 203 kg/s was reached when the air ratio was around 1.2. The optimum air ratio for the operation of a real waste incineration plant is 2-2.5 to keep the flue gas temperature at around 900 \({}^{\circ}\)C in the furnace, which is the ideal temperature value required to meet regulations.  
Figure 5: Flue gas temperature and density with CO2 emissions (simulated in Epsilon).  
Figure 6: Air ratio and CO2 emissions.  
A waste incineration plant in Klemestrud (Oslo, Norway) was used as the bench mark when analyzing the results. This plant works with three lines of grate firing technology; two emit different compositions of flue gas to the third. The mixture entering the treatment facility consisted of 23% of flue glass for two lines and 54% for the third line [31].