Numerical simulation analysis on the characteristics of municipal domestic waste with high calorific value and sludge co-combustion

The combustion characteristics of a high calorific value domestic waste blend with municipal sludge of 350 t/d, 750 t/d, and 900 t/d in three kinds of mainstream mechanical waste incinerators in Guangdong were studied by numerical simulation method, and the model was verified with the operating data. Based on the “3 T” principle of incinerator, the combustion characteristics of mixed fuel with high calorific value municipal solid waste and sludge in different incinerators were analyzed. The results showed that when the maximum blending ratios of sludge in the 350 t/d, 750 t/d, and 900 t/d waste incinerators were 13%, 17%, and 10%, respectively, and the residence times of flue gas in the temperature region above 1123 K were 4.18 s, 3.68 s, and 6.36 s, respectively. The 750 t/d waste incinerator adopts a spiral secondary air injection mode, which is beneficial to the realization of “3 T” principle. The secondary air of the 350 t/d waste incinerator adopts the hedge injection mode, the first flue velocity is larger, and the flue gas residence time is shorter. 900 t/d waste incinerator combined with spiral and hedge injection, the temperature at the exit of one flue decreased by 61.12 K and 132.62 K compared to 0% working condition for 10% and 17% sludge blending, respectively, and the oxygen content increased from 2.97% to 3.91% and 5.63%. The appropriate primary and secondary air ratio and effective secondary air configuration can adjust the incinerator to be in the best operating condition.