Stabilized fuel slurries based on fine coal slime: Rheology, combustion and feasibility study

The paper presents the results on the influence of stabilizing additives on the viscosity, sedimentation, ignition, combustion and emission profile of fuel slurries derived from coal slime. Soy lecithin, sodium lignosulfonate, rapeseed oil, and diesel fuel of 1 wt% were stabilizers. A slurry without stabilizers and with waste turbine oil were tested for a comparison. All the mixtures met the standard viscosity required for pumping and spraying (less than 1,000 mPa·s at a shear rate of 100 s−1). The use of additives reduced the proportion of the separated liquid during fuel storage (up to 6 times). Diesel fuel with a share of 1% reduced the ignition temperature of a fuel slurry by 30 °C and accelerated gas-phase ignition by 10–12%. The slurries with additives of waste turbine oil and sodium lignosulfonate were the most effective. Their integral efficiency indicator was 0.906 and 0.865, respectively. In feasibility study, the transition from bituminous coal to stabilized fuel slurries were analyzed, considering the new technological chain and equipment, the generated power and fuel cost. The cost for the full cycle of preparation of the slurry coal slime–water–soy lecithin will be 7.5% higher than when using bituminous coal. For the rest of the studied fuels, the estimated payback period for capital investments is about 1 year.