Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/946410
20 Tech Quarterly March 2018 Water. desalination + reuse In reverse osmosis (RO) desali- nation, up to 75 per cent of the energy of the plant is used by the high pressure pumps feeding the RO trains. Pump providers are, therefore, continually striv- ing to develop new, more energy e• cient technologies and solu- tions. From e• ciencies of scale, to new, smaller size pumps, to smart plant solutions, the mar- ket is a hotbed of innovation. The key to understanding the energy use of pumps in a desalination plant is to start by looking at the entire plant system. "The most common mistake is not really understanding the whole. A desalination plan is a complete system, you cannot really take a pump as an individual piece of equipment, so you need to be careful to understand the whole system and all of the operating parameters. From our perspective, the best way to do it is to work with our customers, and to really understand their needs," says David Rubio, desalination account manager, Sulzer Pumps Spain. The challenge is to encourage customers to discuss pumping system requirements within the wider context of the desalination plant and its systems. "One of the main problems we've encountered is when the client will only specify ˆ ow-head conditions. That gives us very little room to put forward options that could be better. In desalination, when designing and selecting pumps, no customer, developer, or contractor can really design the plant just around any single equipment, neither the pumps, nor the membranes, it must be a kind of global system," Rubio explains. Capex versus effi ciency The other big topic for discus- sion with customers is, of course, price; and here, again, pump specialists advocate tak- ing a wider and more holistic view of things, to include the performance of the pumps throughout their useful life. "Buyers and procurement man- agers are sometimes unaware that the purchasing price of pumps are only about 10 to 15 per cent of the lifetime cost of the pump, which includes main- tenance costs, repairs, and, of course, energy costs. They don't understand that if they have an energy-e• cient product, a' er two to three years, the higher purchasing price has been more than amortised," explains Uwe Seebacher, director of global marketing and communication at Andritz. The capital expenditure required on high pressure pumps to feed an RO unit certainly can be seen in the broader context of their energy e• ciency, but the really big A well-designed pumping system can play a pivotal part in ensuring the highest possible energy effi ciency in a desalination plant TECH QUARTERLY High energy: how pumps can cut costs in desalination Top tip: Design pumping systems for normal operating conditions 24/7 desalination plant Constantly changing water parameters: temperature, TDS, pH If we are forced to design the equipment around the maximum operating conditions, maybe those conditions are going to happen only a few days a year. It's peanuts." David Rubio, desalination manager, Sulzer Pumps Spain Minimum operating conditions Normal operating conditions Normal operating conditions Maximum operating conditions 20 days/year 20 days/year 325 days/year