# Flue Gas Composition and Treatment Potential of a Waste Incineration Plant
## 2 Methods and Materials
### Theoretical Flue Gas Volume (Emission Volumes)  
For the excess air combustion process which is beyond the stoichiometric, the flue gas volume mainly comprises CO\({}_{2}\), SO\({}_{2}\), H\({}_{2}\)O, N\({}_{2}\), and O\({}_{2}\). The gas volume of the gases can be found as part of the flue gas depending on the elementary analysis of the laboratory results, and following the model can be found in [1].  
Volume of carbon dioxide \(\left(\frac{Nm^{3}of\ C_{\rm O}}{kg\ of\ fuel}\right)\):  
\[V_{\rm CO_{2}}=\frac{22.41}{12}*\frac{C}{100} \tag{6}\]  
The water vapor in the flue gases has two sources; the volume of water vapor from the combustion of hydrogen in the fuel (waste) and the volume of water vapor due to the combustion air humidity, which can be found as follows \(\left(\frac{Nm^{3}of\ H_{2}O}{kg\ of\ fuel}\right)\):  
\[V_{H_{2}O}=\begin{array}{c}\frac{22.41}{100}\left(\frac{H}{2}+\frac{W}{18} \right)\\ \mbox{\it Hydrogen combustion}\end{array}+\begin{array}{c}1.61*\lambda*X*V_{a}^{0 }\\ \mbox{\it air humidity}\end{array} \tag{7}\]  
where \(W\) is the water content of the fuel and \(\lambda\) is the air ratio (excess air which is in the range between 1.2-1.7 for waste incineration plants) [1,20].  
Due to an excess amount of air loaded into the furnace in the excess air combustion process, a new component in the flue gas volume appeared which does not exist in the flue gas volume compared with the stoichiometric conditions:  
The volume of free oxygen introduced in excess air that appeared in the flue gas is \(\left(\frac{Nm^{3}of\ O_{2}}{kg\ of\ fuel}\right)\)  
\[V_{\rm O_{2}}=0.21\ (\lambda-1)V_{a}^{0} \tag{8}\]  
The volume of nitrogen which also has two parts, fuel source and air source, is \(\left(\frac{Nm^{3}of\ N_{2}}{kg\ of\ fuel}\right)\)  
\[V_{N_{2}}=\frac{22.41}{28}*\frac{N}{100}+0.79*\lambda*V_{a}^{0} \tag{9}\]  
The volume of sulfur dioxide is \(\left(\frac{Nm^{3}of\ SO_{2}}{kg\ of\ fuel}\right)\):  
\[V_{\rm SO_{2}}=\frac{22.41}{32}*\frac{S}{100} \tag{10}\]  
The total volume of wet flue gas for combustion with excess air is \(\left(\frac{Nm^{3}of\ flue\ gas}{kg\ of\ fuel}\right)\):  
\[V_{flue\ gas}=V_{\rm CO_{2}}+V_{\rm SO_{2}}+V_{N_{2}}+V_{H_{2}\rm O}+V_{\rm O _{2}} \tag{11}\]  
Flue gas flow rate (m\({}^{3}\)/h) is:  
\[\dot{V}_{flue\ gas}=B*\ V_{flue\ gas} \tag{12}\]  
This model provides the mass flow rate of the flue gas for each kg of fuel. However, this methodology does not consider flue gas generation as a function of its energy content. Furthermore, the calculated fraction of each gas existing in the constitution of the flue gas represents the amount of this gas in each cubic meter emitted from 1 kg of the fuel (MSW). In other words, the calculated CO\({}_{2}\) and SO\({}_{2}\) volumes are functions of the carbon and sulfur content in the waste composition. In this model, N\({}_{2}\) was treated as inert material. It can be said that this model is useful to calculate the mass flow rate of air required to accomplish the combustion process and to calculate the oxygen volume which is essential for the CO\({}_{2}\) specification.