One exemplary embodiment can be a stack for a separation vessel adapted to receive a fluid having one or more phases. The stack may include one or more walls surrounding a void, a packed bed positioned within the void, and a distributor positioned above the packed bed. Generally, the stack has a height greater than its width. Usually, the separation vessel further includes a base having a length greater than its height, and the height of the stack is orientated substantially perpendicular to the length of the base.