Investigation into co-combustion characteristics of dyeing sludge and bituminous coal based on TGA-FTIR

This paper deals with the co-combustion of dyeing sludge and bituminous coal by means of TGA-FTIR. The results show that (1) the co-combustion process mainly consists of three stages respectively corresponding to the de-volatilization and combustion of fiber materials at 150~350 ℃, the combustion of high-molecule polymer materials like bacterium protein at 350~500 ℃ and the calcining of inorganic mineral substancesin the dyestuff above 500 ℃; (2) the addition of dyeing sludge in bituminous coalpromotes the ignition, and a sludge dosage of 30% may result in an ignition temperature decrement of 20 ℃as well as a reduced general combustion parameter; (3) the apparent activation energy in the initial combustion stage of the sludge is only 70 kJ/mol and then increases to 130~160 kJ/mol in the later stage; (4) with the increase of sludge dosage, the apparent activation energy of the blend decreases in the initial combustion stage while increases in the later stage; and (5) comprehensively, the sludge dosage less than 20% only slightly influences the whole combustion process. Moreover, TGA-FTIR results indicate that (1) the mineral substances influence the pollutant emission process in blends via multiple reactions; (2) the alkali oxides and Fe2O3 in the dyeing sludge both benefit the fixation of sulphur in the ash; (3) NOx mainly comes from the fuel; and (4) as the sludge is easy to de-volatilize, a reducing atmosphere consisting of small-molecule combustible gases may form, which helps to suppress the generation of NOx blends in the initial combustion stage. © 2016, South China University of Technology. All right reserved.