Introduction to Flash Dryer for Dye Intermediates

In a rotary flash dryer, heat exchange primarily occurs between the airflow and particles, as well as between the cylinder wall and particles. The drying process fundamentally involves the diffusion of moisture, which includes both external diffusion and internal diffusion. External diffusion refers to the process where moisture on the particle surface evaporates into the surrounding medium, while internal diffusion is the movement of moisture within the particles.

The rotary flash dryer uses high-speed hot airflow introduced tangentially into the cylinder. The swirling motion of the airflow inside the cylinder lowers the temperature around the particles while increasing the medium's flow rate and temperature, significantly enhancing the external diffusion rate. Simultaneously, high-temperature airflow impacts the particles or small wet materials located at the bottom of the cylinder at high speed. The stirring blades inside the cylinder help break the particles into smaller sizes, reducing the length of internal capillaries and enhancing the internal diffusion effect. These particles are repeatedly crushed in the high-temperature, high-intensity stirring zone at the bottom of the cylinder, which prevents material clumping and further promotes internal diffusion, strengthening the evaporation of moisture from the particles.

The flash dryer for dye intermediates is a result of our company’s improvements on similar equipment, achieving the following outcomes:

1. Material Sticking and Bridging: Material sticking to walls and bridging led to discharge issues. After extensive research and testing multiple solutions, our R&D team successfully implemented a motor-driven scraper technology, effectively resolving the problem and achieving mass production.

2. Large Particle Removal: Large particles during the drying process caused severe equipment operational issues. By integrating practical experience, we modified the main unit to include a reverse pressure system for online removal of large particles, successfully solving the problem and achieving mass production.

3. Material Settling: Material settling caused the main unit to jam, hindering normal operation. We redesigned the internal structure of the flash dryer, employed a variable speed motor, and achieved 360-degree coverage within the drying chamber. Parameters were determined during testing and input into the control center, successfully resolving the issue and enabling mass production.

4. High-Requirement Products: For high-demand products in pharmaceuticals, food, and chemicals, multiple dead corners and cleaning difficulties led to non-compliance. Our engineering and after-sales departments jointly developed an online cleaning system for the rotary flash dryer, effectively addressing the problem and allowing for mass production.

5. High Initial Moisture Content: High initial moisture content required larger flash drying equipment, increasing costs and space requirements. Our technical and sales departments collaborated to develop a cyclone drying device with a unique internal structure and multiple loops to extend drying time in a limited space, successfully resolving the issue and achieving mass production.

6. Operational Cost Reduction: To reduce high operational costs and technical requirements while enhancing operational safety, our electrical control team developed an interlinked control system for temperature, airflow, crushing, and feeding devices. This system offers multiple modes (Mode 1, Mode 2, Mode 3), forming a mature semi-automated control solution, effectively addressing the problem and achieving mass production.