Vacuum Catalogue - Edwards

Steam Ejector Vacuum SystemsEdwards has over 90 years experience in the design and supply ofsteam ejector systems. Edwards has been instrumental in thedevelopment of the steam ejector from the relatively crude singlestage devices which evolved into today’s highly efficient multi-stagesystems.Process and mechanical design expertise is combined with projectmanagement skills for the supply of individual items of plant, or theexecution of total projects including installation and commissioning.The company has an immense reputation in applications includingthe following:• Refinery Vacuum Systems • Edible Oil Processing• Vacuum Distillation Units • Polymerization• Flash Evaporation for Seawater • CrystallizationDesalination• Evaporative Cooling• Turbine Condenser AirExtractionFeatures of the Steam Ejector Solution• Low capital cost• No moving parts• Low maintenance• Wide choice of materials• No close clearances• No size limitation• Ability to handle large vapourload• Liquid slugs do not causemechanical damage• Not sensitive to suctiontemperatureOperating PressureSingle Stage 150 – 130 mbarTwo Stage 25 – 15 mbarThree Stage 10 – 7 mbarFour Stage 1 mbarFive Stage 0.1 mbarAs ejectors can be economically manufactured on an individual basisto suit specific customer needs they have a wide capacity range,which is limited only by the manufacturing techniques relevant to thematerial of construction, typically this range would be between10 - 1.5 x 10 6 m 3 h -1 .81276 312Page45451 Strainer 5 Diffuser2 Motive steam 6 Suction3 Nozzle 7 vapour Head4 Discharge 8 Nozzle HolderRangeEjectors can be arranged as multi-stage systems with interstagecondensers, which may be the direct contact type (jet condenser) orsurface type (shell and tube). The multi-stage arrangements allowslower suction pressures to be achieved than could be produced by asingle stage ejector. Interstage condensers economize on the use ofmotive steam, since the operating steam from stages upstream of thecondenser is condensed leaving only saturated incondensable gasesto be handled by the succeeding stage or stages.4Interstage Jet CondensersJet or spray type condensers operate by condensing steam by directcontact with the cooling water. This type of condenser can be locatedat barometric height or at low level using a condensate extractionpump. Jet condensers tend to use less cooling water than surfacetypes, although as the ejected vapours are in contact with the coolingwater the treatment of any resulting effluent must be considered.Interstage Surface CondensersSurface condensers of the shell and tube type perform the samefunction as jet types, however the ejector steam and process vapoursare condensed on the tube surfaces without contact with the coolingwater, greatly reducing the potential effluent problem. Removableend covers on the condensers allow easy cleaning of the tubes.Shop online at www.edwardsvacuum.com