Advancements in spray drying system for heat recovery, methodology, and economics: A review

Spray drying systems with heat recovery have gained prominence in recent times due to the energy crises and changing weather conditions. These systems are widely used in various industries, including chemical, food, fertilizer, and pharmaceutical, but their energy-intensive nature calls for efficient operation and heat retrieval. This review article discusses the current developments in heat recovery methods, including direct, indirect, and hybrid systems, as well as improvements in dryer efficiency and thermal optimization techniques. Pinch and exergy evaluations are extensively investigated as they play a crucial role in heat integration design and analysis. Recovering heat from the exhaust stream of spray dryers poses challenges due to fouling caused by fines in the exit stream and the selection of analysis methods. Exploring non-conventional energy sources like solar and geothermal energy shows potential for drying operations, but further research is needed for design and control. The adoption of recovery options has led to a 35% improvement in energy efficiency and around 74% energy savings in specific cases.