| abstract |
Fuel is burned in a primary combustion zone so that a substantial quantity of unburned hydrocarbons, such as carbon monoxide (CO) is produced along with some nitrogen oxides (NOx) and whereby essentially no oxygen remains at the completion of the combustion process. The gaseous combustion products are conducted through a gas dispersion matrix or bed in which the unburned hydrocarbons and NOx react to produce carbon dioxide (CO2) and nitrogen (N2). Air is then injected into the gases in a secondary combustion zone to oxidize the residual unburned hydrocarbons to CO2 in which case the exhaust gases are substantially free of air polluting CO and NOx. |