(77b) Effective Control of Residual Solvents In API Drying Using Fluid Bed Dryer

The demand for the API has increased significantly in recent years, thus, additional drying capacity and alternative drying technology is required to meet the increased demand. This led us to develop an alternative and more efficient drying technology to dry the wet cake. Fluid bed dryer (FBD) was chosen because it allows for faster drying and produces a consistent particle size distribution. The API wet cake, isolated from a mixture of water, ethanol, small percentage of heptanes and other solvents, has a LOD approximately 50% and can be dried with a fluid bed dryer in approximately 3 hours instead of over 40 hours using a vacuum agitated dryer.

We will present the detailed development and scale-up of FBD drying technology to dry the API wet cake, from lab scale to production scale. Many obstacles have been overcome successfully, especially the removal of residual heptanes to minimize environmental emissions and to improve product quality. Heptanes in the wet cake can be effectively removed in the original agitated vacuum dryer. However, due to the fast drying without vacuum in FBD, the residual heptanes are slightly elevated after FBD drying. On the other hand, a small amount of heptanes is needed in the precipitation step to produce the desired wet cake properties suitable for FBD drying. We will discuss the details on how we resolved this technical challenge. The result of this work significantly increases the throughput of API drying in commercial production.