Study on thermal behavior and gas pollutant emission control during the co-combustion of waste tire-modified oily sludge and coal

Abstract

Oily sludge, a hazardous byproduct of oil processes, poses significant environment and human health when improperly managed. This study examines the thermal behavior and gaseous emissions during co-combustion of oily sludge modified with waste tire powder (OS₇-T₃) and coal, using an automatic calorimeter and along with kinetic modeling. Additionally, the synergistic effects of co-combustion, as well as the gas emissions under varying oxygen concentrations, heating rates, and the influence of additives, were thoroughly examined. The results indicate that an increase in OS₇-T₃ content leads to a reduction in the performance of mixed fuel. When the OS₇-T₃ content reaches 30 %, the calorific value of combustion exceeds 20 MJ/kg, with no substantial decrease in the combustion index. The application of additives effectively mitigates pollutant gas emissions. Increasing the heating rate from 5℃/min to 20℃/min significantly enhances combustion performance, improving it by 4.19 times. Likewise, an increase in oxygen concentration from 10 % to 100 % results in a 2.97-fold increase in the combustion index. Montmorillonite reduces the emissions of pollutant gases by absorbing polar molecules. BaO and CaO effectively mitigate H₂S and SO₂ emissions but have limited influence on the control of NO and NO₂ emissions. These findings strongly support the co-processing of oily sludge in cement kilns, facilitating its environmentally friendly disposal and promoting efficient resource utilization.