Thermodynamic analysis of a prototype indirect screw drier for aggregates and recycled mineral aggregates

In this paper is presented an industrial drier developed, prototyped, tested and analyzed to produce selected aggregates for the construction industry, for a localized and specific production line for the treatment of natural or recycled aggregates. The short production of premixed powder, through the exploitation of local and recycled aggregates, has highlighted the need to design an efficient drying system. The prototype developed as a drier (Screw Conveyor Drier-SCD) with screw at an angle of 20°, 2000 x 3685 mm 7070 x size, isolated outside of indirect heat exchange. The fluid exchanges heat in the circuitry that runs through the inside of the shaft and the outer sleeve of the auger. The type of heat source is not binding; therefore, sources of renewable energy or waste heat can be used, even at low specific enthalpy. During experimental analysis, hot water was used at a maximum temperature of 80 °C and sand with 5-6% moisture input was processed for a flow rate of 2 tons/h. Experimental results have shown, in a two-stage step, a reduction in the humidity up to 30% compared to the initial value and a maximum temperature of 31 °C in solid output. The analysis of experimental results and the data obtained from thermodynamic simulations have shown that the system performance can be optimized through specific improvements of the mechanical parts