Co-combustion characteristics of sewage sludge with different rank bituminous coals under the O2/CO2 atmosphere

The effects of sewage sludge (SS) blended ratio, O2/CO2 ratio, and type of bituminous coal on the co-combustion characteristics of SS with bituminous coals were investigated. Thermogravimetric analysis was used to analyze the co-combustion profiles. Results show that TG curve shifts to a lower temperature with increasing SS blended ratio and O2/CO2 ratio. A distinct transition section exists at fixed carbon combustion of the blended fuels stage, and the temperature range of this transition section decreases significantly with increasing O2/CO2 ratio. The combustion property indexes of blended fuel increase with increasing SS blended ratio and O2/CO2 ratio. However, effect of O2/CO2 ratio on increasing the overall co-combustion characteristics becomes smaller when the oxygen concentration exceeds 30 %. Comparing SS blended with Huaibei (HB) bituminous coal, the SS blended with Shenhua (SH) bituminous coal (high-rank bituminous coal) combustion has the good combustion performance.