A process line for the production of freeze-dried particles under closed conditions, the process line comprising at least a spray chamber for droplet generation and freeze congealing of the liquid droplets to form particles and a bulk freeze-dryer for freeze drying the particles, the freeze-dryer comprising a rotary drum for receiving the particles. Further, a transfer section is provided for a product transfer from the spray chamber to the freeze dryer, and for the production of the particles under end-to-end closed conditions each of the devices and of the transfer section is separately adapted for operation preserving sterility of the product to be freeze-dried and/or containment. Fig. 3
