Volumetric scaling up self-sustained smouldering of printing and dyeing sludge with high moisture content

Abstract

Smouldering is a novel low-energy, low-cost and high-effective technology for the disposal of high-moisture wastes. Most of the existing reports focus on the lab-scale studies and non-continuous operation, but the study about the large-scale device and continuous process is lacking. This work scales up the self-sustained smouldering from the lab-scaled device to the pilot-scale device for treating the printing and dyeing sludge (PDS) with high moisture (over 60%) under continuous operation. Firstly, the lab-scale smouldering experiments with different sand/PDS mixing ratios are performed, and the 4.5/1 mixing ratio is selected as a suitable mixing ratio. Then, the pilot-scale smouldering experiments are carried out and the influence of the discharging residual interval (50s, 35s, 20s) on the reaction stability is tested under continuous operation. Results indicate that the 35s for discharging residual interval may be suitable to maintain the high-temperature region at a relatively stable location under the studied operating condition. The flue gas concentrations are relatively stable during discharging residual, and the main component concentrations are 17.0–17.8% for O2, 2600∼3000 ppm for CO, 20∼35 ppm for VOCs, and 60∼80 ppm for NOx, 0.0415–0.0836ngTEQ/m3 for dioxin, respectively. The research in this study can give helpful information for the application of the continuous smouldering treatment in the future.