Water. desalination + reuse

TECHNOLOGY • • • • staff training compared to large CF pumps, which require specialized factory trained technicians and/or shipping equipment back to factory for maintenance and repairs. This will significantly decrease downtime in facilities using AP Pump technology. No huge VFD or RVS are required. AP Pumps can be started across the line (depending on country and electrical supply requirements) due to the smaller individual motors. No regulating valve or VFD is required to control AP pumps, which further improves the overall system efficiency compared to CF pump process designs. Low voltage power can be used to drive smaller motors arranged in a modular array. Virtually eliminates in rush current associated with starting large electric motors. • • • Smaller individual pumps arranged in a modular array allow for additional system flow control by turning pumps on or off within the array while maintaining peak efficiency and optimal power usage. Multiple-small diameter discharge check valves are less expensive and have less lead time than large, exotic alloy valves due to the specialized nature of the large valve industry. No complex shaft alignment required with close coupled AP pumps DisaDvaNTaGEs • More plant space may be required for the AP pump modular array, though less electrical space will be required. • Longer installation and commissioning period may be required due to multiple pumps and components • • • • Multi-start system opposed to one larger CF pump may lead to a longer start-up time. More instrumentation may be required, but will provide additional data for troubleshooting and system efficiency monitoring. The efficiency of CF pumps increases with flow rate reducing the efficiency advantage of the modular AP pump concept at the higher end. Additional spare parts, maintenance and down time are needed although the service intervals are predictable. Reference 1. The Affordable Desalination Collaboration 10 MGD Conceptual Case Study, Seacord, Dundorf, MacHarg, American Membrane Technology Association (AMTA) Annual Conference Proceedings 2007 More and more SWRO plants running parallel trains _________ Danfoss rO solutions, Netherlands ___ Editor's Note: An increasing number of new SWRO plants comprise at least two and often three or more parallel trains. Danfoss confirms the trend, and reports that more and more small and medium-sized plants – even containerized solutions – are specifying multiple trains. TRENDSPOTTERS in the seawater reverse-osmosis (SWRO) industry have long predicted that parallel trains would make their way from large-scale municipal plants to small and mediumsized plants. Now, reports from equipment manufacturers and system integrators indicate that the vision is fast becoming a reality. "The trend toward parallel trains is pretty clear," explains Jesper Bentzen, global sales director at Danfoss. "Since so many small to medium-sized SWRO plants are in remote locations – often extremely remote – the redundancy provided by parallel trains is something that a lot of operators just don't want to live without." "Our iSave has all the advantages of energy-recovery device (ERD) systems that are much more complex – but it is simpler, has fewer parts that can break down, and takes up just a fraction of the footprint," Bentzen points out. "We're seeing strong iSave sales across the board, but especially in parallel train setups where space is a key issue, such as containerized plants." THrEE-iN-ONE CONsTruCTiON Danfoss launched the patented iSave in 2009 as the first isobaric ERD to be | 32 | Desalination & Water Reuse | November-December 2013 fully integrated with its own positive displacement booster pump and electric motor. This makes the ERD both compact and maintenance friendly, in addition to being extremely efficient – up to 93%. Danfoss's device reduces energy consumption by up to 60% by harnessing pressure from the membrane reject flow and transferring it directly to the membrane feed flow. Since a high-pressure positive-displacement booster pump and an electric motor are integrated with the isobaric pressure exchanger, the iSave needs no flow meters

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