A sieve bed including an inlet end, an outlet end, a retainer disposed toward the inlet end and including an interior portion, an exterior portion, a plurality of openings disposed toward the exterior portion, and a passage disposed toward the interior portion, an inlet cap and an inlet port configured to receive a feed stream, wherein the inlet cap includes at least a portion spaced from the retainer thereby defining an inlet chamber in fluid communication with the inlet port and the plurality of openings, an outlet lid disposed toward the outlet end, an exterior wall extending from the inlet cap to the outlet lid, an intermediate wall spaced from the exterior wall and extending from the retainer toward and terminating short of the outlet lid and an interior wall spaced from the intermediate wall and extending from the retainer proximate the passage to at least the outlet lid.