Comparison of multiple port and end port connections for pressure vessels

The design of reverse osmosis and nano filtration plants is essentially influenced not only by the module arrangement, but also by the arrangement of the pressure vessel connections. Multifarious design possibilities can be considered as a result of many improvements introduced over the last few years. The key attributes is the three purposes port arrangement, feed-, concentrate- and permeate connection while comparing multiple port versus end port design. The following paper discusses the main factors for future plant design: • Cost savings by reducing the complexity of stainless steel piping in multiple port design. • The impact of the more compact design on total foot print required for the membrane plant, • How can technical risks, especially corrosion, be considerably reduced, and • The impact of the hydraulic design of the entire piping system and its influence on energy costs.

(a) The design of multiple port vessels cuts 50% of the stainless steel piping costs while keeping vessels costs at the same price level (may slightly change from supplier to supplier). (b) Multiple port solutions needs smaller foot print and space, especially in containerized solutions. (c) Maintenance and repair works are faster and re-start step is safer and shorter as no piping dismantling and re-assembling work is required. (d) By leaving out the manifold on the rack, the corrosion impact is extensively reduced. (e) By using a multiple port design, the pressure loss, created by manifold and piping is at least three times higher in case of an end port vessel system. Multiple ports design can save up to ten times on energy cost. (f) Operators should consider operating expense as well as capital expense.