Analysis of heat recovery from a spray dryer by recirculation of exhaust air

• We study a spray dryer with heat recovery by partial recirculation of exhaust air.
• We examine effects of process parameters on energy efficiency and energy savings.
• Decreasing drying air temperature and flow rate will increase energy efficiency.
• Increasing recirculation ratio and slurry feed rate will increase energy efficiency.

Model simulations were employed to investigate the influences of process parameters on the energy recovery in spray drying process that partially recycle the exhaust drying gas. The energy efficiency and energy saving were studied for various values of recirculation ratios with respect to the temperature and flow rate of the drying air, slurry feed rate and concentration of slurry in spray drying of advanced ceramic materials. As a result, significant gains in energy efficiency and energy saving were obtained for a spray drying system with high recirculation ratio of exhaust air. The high slurry feed rate and the low slurry concentration, inlet drying air temperature and drying air flow rate enhanced the energy efficiency of spray drying system. However, the high energy saving was obtained in spray dryers operating at low slurry feed rate and high slurry concentration.