Full Description

The 8-inch diameter x 40-inch long spiral wound reverse osmosis (RO) element is used widely today formunicipal RO systems. However, this 8-inch element is clearly not the optimum for alarge plant. It has long been recognized that the number of elements, pressure vessels,pipe connections and O-rings required for a large RO plant is unreasonable.Additionally, a system based on 8-inch diameter elements requires significantly morefootprint than a system based on larger diameter elements. Elements that are larger thanthe 8-inch x 40-inch element have been produced for some specific projects over theyears, but large elements have not been fully commercialized in the past due to concernsrelated to manufacturing, operations and maintenance.This paper discusses the issues related to the manufacture and use of large elements,and demonstrates how these challenges have been addressed for an element that is 18-inches indiameter x 61-inches long. This element has seven times the membrane area of a typicalRO element and therefore allows for a significant reduction in the number of componentsand the size of the RO system footprint. Since the flow capacity and forces on theelement are proportional to the square of the element diameter, certain aspects of astandard spiral element required review and selection of alternatives. The authors discussthe choice of number and attachment of the component leaf units, the choices for thecentral core tube and inter-element connection system, and how the elements aresupported within a multi-element housing against flow induced differential pressure. Theauthors also show how loading and handling issues dictate departures from traditionalspiral element design. Results of in-house and field testing show how this large scaleelement meets the challenges related to operation and maintenance of an RO system. Includes 4 references, table, figures.

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Edition: Vol. - No. Published: 03/01/2005 Number of Pages: 18File Size: 1 file , 910 KB