Abstract: Theexisting technical challenges of high steam consumption, low drying efficiency, and uneven heat transfer in the operation of rake dryers, as well as large material loss caused by the residual filter residue layer inside the cylinder make it difficult to meet safety, environmental protection, and GMP requirements. Aiming at these technical difficulties, an efficient and energy-saving rake dryer was designed, and a lightweight internal and external cylinder and blade composite heating stirring shaft structure was independently proposedafter literature review and extensive experimental research.The central rotating shaft, connecting shaft, and stirring blade were all hollow in design with a clearance of 3-5 mm between the scraping part of the blade and the cylinder wall. The required stirring power has been significantly reduced;the heat exchange area is large and the heat transfer efficiency is high, achieving the goals of no residual materials, reducing production costs and ensuring complete isolation of people and materials. This can meet the GMP requirements of the pharmaceutical industry. The actual experimental research results show that the drying reduction ratio reaches 19.9%; the steam unit consumption is 32.8% and the energy consumption is significantly reduced. It indicates that this method and equipment are of high value for promotion and application.

Key words: vacuum rake dryer, composite heating, mixing device, energy conservation, GMP