A powder processing apparatus includes a vessel. The vessel has an interior chamber that includes top and bottom regions, and a gas outlet to the exterior of the vessel. A wall divides the bottom region into first and second sub-regions, with the top region extending above the wall. First and second porous plates divide the first and second sub-regions such that there are first and second manifold regions below the first and second porous plates. The first and second gas manifold regions include first and second gas inlets from the exterior of the vessel.