3-DIMENSIONAL SIMULATION OF AIR MIXING IN THE MSW INCINERATORS

Combustion control strategies to minimize the pollutants emission from municipal solid waste (MSW) incinerators are formulated based on the improved mixing of air with the products of incomplete combustion and the subsequent increase in oxidative destruction. Secondary air inject ion into the combustion chamber plays the key role in this mixing proc ess. However, design variables of the air jet into the combustion gas stream are not clearly identified, and the performance of mixing and r eaction is not fully understood. Three-dimensional flow simulation was performed to study the mixing performance of a full-scale incinerator combustion chamber according to the secondary air nozzle configuratio n. A detailed flow was analyzed and the degree of mixing was quantitat ively evaluated by introducing a statistical parameter based on the ch emical species distribution. The gas residence time distribution was a nalyzed using the particle trajectory. The overall how held was strong ly influenced by the nozzle configuration. It was demonstrated that th e degree of mixing could be improved by selecting larger inter-jet spa cing and stronger jet velocity. The staggered arrangement of two oppos ite nozzle arrays was found to be more effective in terms of mixing an d gas residence time distribution.