A Study on Coal Ash Slurry Flow at Higher Solid Concentrations in Pipeline

Abstract

In India, thermal energy accounts for more than 70% of electricity production and millions of tons of coal are burned in these thermal power plants. Thus, large quantities of coal ash (fly ash and bottom ash) are produced and the current level of production is about 120 million tons per year. Out of this, approximately 20% is bottom ash and the rest 80% is fly ash. The ash produced in India usually has higher specific gravity as Indian coal has a much higher content of non-combustible matter. Also, the majority of the thermal power plant in India disposes of both the materials, namely fly ash and bottom ash to ash ponds using the same pipeline. The knowledge of slurry rheology is very vital for the design of a slurry pipeline particularly for the dense phase conveying system. Since the pilot plant loop tests at these concentrations are tedious, time-consuming, and complex in nature, the slurry pipeline designers have been adopting the empirical approach for slurry pipeline design based on the rheological model of the slurry. From the vast study of literature, an attempt has been made to highlight the various influencing parameters like concentration of solid, rheological properties, and chemical additives that affect the flow of coal ash slurry in the long-distance pipelines.