NOx Emission Characteristics During Decoupling Combustion of Municipal Solid Waste in a Grate Furnace

As the stringent flue gas emissions limit and the withdrawal of state subsidies, the waste incineration industry is in urgent need of efficient and clean new technologies. In this paper, based on the principle of decoupling combustion (DC), a drying/pyrolysis zone was constructed by circulating reheated flue gas in a 300 t/d waste incinerator, in order to reduce NOx formation. The results showed that the effect of circulating reheated flue gas (270◦C) injected into the first and second parts of fire grate of the incinerator is better, and the NOx concentration in the flue gas can be controlled below 200 mg/m3 (standard condition); With the increasing of the amount of reheated flue gas, the reduction of NOx formation decreased. It would adversely affect the incineration conditions if ratio of circulating flue gas to total flue gas exceeded 6.22%. Compared with traditional combustion (TC) and flue gas recirculation (FGR) technologies, the decoupling combustion (DC) could better suppress NOx generation, and NOx formation was reduced by 43.1%. The DC had no significant effect on the heat loss rate (or residual carbon amount) of bottom ash, and the O2 content in the flue gas dropped to 2/3 of TC. The operating cost of DC for one ton waste was found to be 5 yuan less than that of TC, which is of great significance for the regulation of waste incineration operation and energy-saving renovation. © 2024 Science Press. All rights reserved.