Performance evaluation of a rotary dryer in both co-current and counter-current configurations

Abstract

A mathematical model was developed to simulate the process of superphosphates fertilizers drying in a rotary dryer in both co-current and counter-current configurations. Besides, the performance of the rotary dryer, installed in a local industrial unit, was assessed using the concept of energy and exergy analysis. Matlab software was used to develop the mathematical model, which is based mainly on mass and energy conservation equations. Good agreement between the simulated results and the experimental results from literature was obtained. The simulation results showed that the product’s moisture content was reduced from an initial value of 0,14 kgH2O / kg dry solid to 0.0912 and 0.0862 kgH2O / kg dry solid at the dryer's outlet for the co-current and the counter-current configurations, respectively. A parametric study was carried out to evaluate the effect of the length of the dryer and the inlet drying air temperature on the moisture content to compare both configurations. Energetic and exergetic indicators were formulated and then computed based on the inlet operating conditions. The energy efficiency and the specific energy consumption for the co-current and the counter-current configurations were, respectively, found to be 13% and 24% and 5762 and 3502 kJ per kg of water evaporated. The exergy indicators, namely the exergy loss, the exergy destruction rate, and the exergetic efficiency, were 11.37 and 17.82 kW, 1.026 and 1.098 kW, 25.86 and 41.38% for the co-current and the counter-current configuration, respectively. A sensitivity analysis was used to investigate the effect of varying the inlet drying air temperature on energetic and exergetic performance parameters.

Keywords

• Co-current
• Counter-current
• Energy and exergy analysis
• Mathematical model
• Rotary dryer
• Superphosphate fertilizer

References

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