Rheological characteristics and stability of fuel slurries based on coal processing waste, biomass and used oil

Abstract

The paper presents experimental research findings for the viscosity and stability of fuel slurries. Thirty compositions produced from coal sludge, lignite and bituminous coal were studied. Wood sawdust, used turbine oil, starch, neonol, xanthan and guar gums were used as additives. The viscosity of the fuel compositions varied from 106.89 to 2030.17 mPa∙s at a shear rate of 100 s−1. Adding up to 10% used oil or wood sawdust increased the slurry viscosity by 50–70% on average. When the shares of oil and biomass exceeded 5% and 10%, respectively, the slurry lost its fluidity. It was found that the mass fraction of the solid part in fuels based on coal sludge should be limited to ≈55%, if spraying or pipeline transportation is planned. A multifactor evaluation of the fuel mixture efficiency was performed using six different variations of distributing the significance (weight coefficient) of the factors under consideration. It was established that fuel mixtures based on coal sludge (i.e., coal processing waste) and water are the most preferable ones. It is shown that the viscosity of many fuel mixtures based on coal sludges corresponds to the conditions of industrial application of fuel slurries and liquids. The obtained findings may be applied when planning and optimizing the operating procedures at thermal power stations and boiler units intended for slurry fuel combustion. In particular, the results can improve the preparation, storage, transportation, and spraying of high-moisture fuel mixtures based on waste and low-rank materials.