Hydrodynamic and heat transfer studies using quarry dust and iron ore particles for waste heat recovery

Waste heat recovery is a key element for an industry to operate successfully and sustainably, as energy costs significantly impact the decision-making process. A SP (suspension preheater) system has played a significant role in recent advances in the cement manufacturing industry. The suspension preheater and pre-calcinator used in modern dry processes cement plants reduce specific energy consumption to as low as 800 kcal/kg clinker. A metallic gas-to-particle direct-contact heat exchanger was utilized to experiment with quarry dust and iron ore particles. Calculating acceleration lengths requires plotting pressure gradients against riser height. An empirical correlation is fitted to the acceleration length ( L A ) measured at different parametric levels ( u g , d p , w s , and ρ p ). Throughout the riser, the temperature was measured at various stages for both gases and solids. In a hot model, particle size and flow rate of solids and gas were varied extensively in order to study heat transfer. At different solid and gas flow rates, quarry dust and iron ore heat transfer rates and heat transfer coefficients are determined. The Nusselt number correlation was developed using regression analysis. Various other industries are expected to benefit from this study, as well as reusing waste heat from gases.