Energy and exergy analysis in an asphalt plant’s rotary dryer

Abstract

a b s t r a c tIn this paper, energy and exergy analyses of a rotary dryer employed in a Hot Mix Asphalt (HMA) plant for heating and drying of the aggregates in the mixture is presented. In the analysis, the exergy method in addition to the more conventional energy analysis, is employed to identify and evaluate the ther modynamic losses. The results show that, at design conditions, the plant performs with energy and exergy efficiencies of 0.89 and 0.18, respectively. The energy losses are mainly due to the flue gases. The exergy distribution indicates that the combustion and the heat transfer at different temperatures in the burner yield the highest exergy destruction in the process. A parametric study is conducted for the plant under various operational production parameters, including different humidities of the aggregates and filler content in aggregates, working temperatures and ambient conditions, in order to determine the parameters that affect the plant performance. It is shown that the solids humidity has a great impact on energy requirements. A better and sustainable use of the heat source employed in the dryer is proposed to avoid the high irreversibilities found. Furthermore, operating corrections in the mix or in the exhaust gas temperature are proposed to optimize the performance of the plant.

Rheological characterization of wax modified bituminous binders: Effect of specimen preparation and thermal history

“…Wax additives can significantly reduce the asphalt mixing and pavement construction temperatures [8,9], creating remarkable environmental benefits to the asphalt industry [10]. It is mainly due to these environmental aspects that the use of commercial waxes in bitumen modification has vastly increased during the past decade [11,12].…”

Convective heat transfer analysis in aggregates rotary drum reactor

“…To the best of our knowledge, except few numerical works based on a global analysis [10] or a CFD tool [11], very few previous studies [12] have treated of the heat transfer analysis inside large-scale rotary drum dryer. Despite the size difference between particles and aggregates, the work of Leguen et al [13] show that the granular mixing in the bulk flow (see Fig.…”

Application of solar aggregate stockpiles in the process of storing recycled materials

“…If such preheated mineral mixture is used, it is possible to calculate potential energy savings of 2.7 kWh, which is 4.3% of the total energy requirements in the production of 1 ton of HMA . Peinado et al gave a rough estimate of an energy requirement of 2.62 kWh for every additional 10°C increase in asphalt temperature. By using a preheated mineral mixture with a 14°C higher input temperature compared with the mineral mixture temperature, the energy required to remove moisture content can be reduced by 2.2%.…”