Underdrain for media vessel and method of cleaning
An underdrain system for a media pressure vessel has a set of removable pipe sections located between an external header and the bottom of a vessel. Septa extend upwards from the removable pipe sections into the vessel. The header is attached to the bottoms of the removable pipe sections. Each pipe section, and its associated septum, may be removed individually. To clean the vessel, after media is removed from the vessel the pipe sections are removed sequentially while the header remains otherwise attached to the vessel. While a pipe section is removed, its associated septum is removed so that solids can be removed from the annulus between the septum and the vessel. In this way, media can be cleaned from the annuli without moving the external header or entering the vessel.
1 . A method of cleaning a media pressure vessel comprising
the steps of,
removing one or more pipe sections of a plurality of pipe sections from between an external header and a bottom of the vessel while the header remains attached to the vessel by one or more remaining pipe sections of the plurality of pipe sections, one or more attachment members extending between the header and the bottom of the vessel, or both; and,
removing one or more septa of a plurality of septa from the vessel, wherein each removed septum is removed from the vessel by lowering the respective septum into a space previously occupied by a corresponding one of the removed pipe sections; and
cleaning the media pressure vessel by removing solids from respective portions of the vessel exposed by said removing the one or more septa from the vessel.
2 . The method of claim 1 comprising replacing the removed one or more septa and the removed one or more pipe sections and then removing one or more further pipe sections of the plurality of pipe sections and one or more further septa of the plurality of septa from the vessel.
3 . The method of claim 1 wherein the header remains attached to the vessel during said removing the one or more pipe sections by the one or more remaining pipe sections.
4 . The method of claim 1 wherein said removing the one or more pipe sections comprises moving the one or more pipe sections sideways away from the header.
5 . The method of claim 1 wherein said removing the one or more septa comprises moving each removed septum sideways away from the header after the respective septum is lowered into the space previously occupied by the corresponding removed pipe section.
6 . The method of claim 1 , wherein each removed septum is shorter than the corresponding removed pipe section.
7 . The method of claim 1 , wherein the header remains attached to the vessel during said removing the one or more pipe sections by the one or more attachment members.
8 . The method of claim 1 , each pipe section extends vertically between the header and the bottom of the vessel.
9 . The method of claim 1 , wherein each pipe section comprises a lower flange removably attachable to a corresponding one of a plurality of inlet flanges of the header.
10 . The method of claim 1 , wherein each pipe section comprises an upper flange removably attachable to a corresponding one of a plurality of flange pads of the vessel.
11 . The method of claim 2 , further comprising, after said removing the one or more further septa, removing solids from respective portions of the vessel exposed by removing the one or more further septa from the vessel.