A freeze drying vessel (302) having a freeze drying chamber (304) that includes sloped horizontal shelves (352) that receive frozen particles (282). Each shelf is sloped relative to a horizontal axis (390) and arranged such that a downward slope between successive shelves alternates between first (392) and second (394) directions. At least one connecting member (374, 376, 378, 380, 382, 384, 386, 386, 388) is attached between pairs of shelves. At least one connecting member is attached to an associated vibration element (396, 398, 400, 402) located outside the drying chamber. Each vibration element vibrates a pair of shelves to cause the frozen particles to advance relative to an associated shelf and drop downward from shelf to shelf wherein the shelves heat the frozen particles to promote sublimation to form freeze dried product (284).