Numerical simulation of gas-solid two-phase flow in the spin flash drying process

Spin flash drying is a crucial step in the preparation of molecular sieves. The gas-solid two-phase flow in the drying tower is an important factor affecting the drying efficiency and product quality. Using the discrete phase model (DPM), the gas-solid two-phase flow and distribution inside a spin flash drying tower were calculated by numerical simulation methods. The influence of different operating parameters on the gas–solid two-phase flow and particle residence time in the drying tower was analyzed. The results show that the particles in the drying tower exhibit a distinct swirling motion. The particle distribution is uneven with a dense edge and a sparse center. Increasing the operating gas velocity can significantly increase the gas flow rate in the drying tower and reduce the average particle residence time. The influence of the spray angle of the atomizer on the average residence time is generally not significant. However, if the spray angle is too large, particles may come into contact with the dry tower wall prematurely, resulting in scaling on the inner wall. The influence of the spray height on the average particle residence time is also relatively small. However, if the spray height is too low, particles are likely to accumulate at the bottom of the drying tower, which will affect product quality.