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STEAM EJECTOR VACUUM SYSTEMS
BOC Edwards has over 90 years experience in the design and supply of steam ejector systems. BOC Edwards has been instrumental in the development of the steam ejector from the relatively crude single stage devices which evolved into today’s highly efficient multi-stage systems. Process and mechanical design expertise is combined with project management skills for the supply of individual items of plant, or the execution of total projects including installation and commissioning. The company has an immense reputation in applications including the following:
Range
Ejectors can be arranged as multi-stage systems with interstage condensers, which may be the direct contact type (jet condenser) or surface type (shell and tube). The multi-stage arrangements allows lower suction pressures to be achieved than could be produced by a single stage ejector. Interstage condensers economize |
on the use of motive steam, since the operating steam from stages upstream of the condenser is condensed leaving only saturated incondensable gases to be handled by the succeeding stage or stages.
• Refinery Vacuum Systems
• Vacuum Distillation Units
• Flash Evaporation for Seawater Desalination
• Turbine Condenser Air Extraction
• Edible Oil Processing
• Polymerization
• Crystallization
• Evaporative Cooling
Features 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 vapor load
• Liquid slugs do not cause mechanical damage
• Not sensitive to suction temperature |
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Interstage jet condensers
Jet or spray type condensers operate by condensing steam by direct contact with the cooling water. This type of condenser can be located at barometric height or at low level using a condensate extraction pump. Jet condensers tend to use less cooling water than surface types, although as the ejected vapors are in contact with the cooling water the treatment of any resulting effluent must be considered.
Interstage surface condensers
Surface condensers of the shell and tube type perform the same function
as jet types, however the ejector steam and process vapors are condensed
on the tube surfaces without contact with the cooling water, greatly reducing
the potential effluent problem. Removable end covers on the condensers
allow easy cleaning of the tubes.
Multistage ejector/liquid ring pump combinations
BOC Edwards are able to offer combinations of steam ejectors and liquid ring pumps where the liquid ring pump replaces the final stage or stages of a steam ejector system. This enables large vapor/gas flows to be handled at the low pressures associated with multi-stage steam ejector sets whilst substantially reducing steam consumption and hence operating costs.
Ejector and ejector liquid ring pump combinations can be supplied using BOC Edwards designed liquid ring pumps. The depth of experience in both types of equipment allows optimization of the equipment both in performance and economy of utilities.
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Applications and design services
BOC Edwards offers a comprehensive design service based on unrivalled
process vacuum experience, application knowledge and design capabilities.
In order to propose a solution the following information is required at the
enquiry stage:
• Suction flow
• Composition and Molecular weight
• Suction pressure
• Discharge temperature
• System volume
• Evacuation time
• Discharge pressure
• Motive pressure and temperature, max-normal-min
• Cooling water temperature, max-normal-min
• Type of condenser direct or indirect
• Type of installation Barometric or low level
• Materials of construction
• Design codes applicable
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