Enhanced destruction of CH₃Cl in postflame combustion gases

Chlorinated hydrocarbons (CHCs) are some of the most difficult chemicals to incinerate. Regulatory requirements mandate destruction and removal efficiencies greater than 99.99%. High-temperature conditions needed for these destruction efficiencies also result in the formation of nitrogen oxides, as well as the possible formation of other hazardous pollutants such as dioxins. Reducing the temperature reduces the formation of NOx, but may lead to incomplete combustion of the wastes. In addition, incinerator temperatures outside the flame zone (averaging about 1000 K) may enhance byproduct formation in the presence of sufficient oxygen, even if the waste itself is destroyed. Experimental and numerical modeling results show that the concentration of CH3Cl in the exhaust gas influences the extent of destruction. There is an optimal concentration level (100 ppm) where CH3Cl is most effectively destroyed in the postflame region of our reactor. Levels higher or lower are more difficult to destroy in our system. The results indicate that the injection of fuels to the postflame region can increase the destruction efficiency or reduce the peak temperature needed for adequate destruction of CH3Cl by increasing the radical concentrations and the rate of subsequent destruction reactions. The postflame fuel injection not only enhances the destruction of initial compounds, but also helps destroy the byproducts.