In many regions of the world, the lack of freshwater resources has become a critical concern. Urban populations are growing, which adds to the challenge. Providing access to clean freshwater is critical for a sustainable city life.
Seawater desalination is an important means of providing a sustainable supply of freshwater. Although the clean freshwater is used for different purposes, such as industrial and agricultural processes, 60% is devoted to human consumption. Because energy is the largest single expense for desalination plants, companies are looking for energy-efficient solutions.
Sulzer’s pumps for seawater desalination are market leaders in terms of efficiency. Hence, the company supports its customers in supplying clean freshwater in a cost- and energy-efficient manner.
From Seawater to Freshwater: Providing Equipment for Desalination Plants
Seawater desalination is a promising and fast-growing solution to counter water scarcity. Reverse osmosis—a desalination technology—requires less energy and is less expensive than other methods. By providing highly efficient pumps, Sulzer facilitates the affordable and energy-efficient supply of freshwater.
The current climate change scenario predicts that almost half of the world’s population will live in areas of high water stress by 2030. Population growth and industrialization in developing areas are substantially increasing water demand. Governments, national, and international institutions, as well as water management companies, are looking for solutions to face one of the most pressing challenges that lies ahead. Since seawater represents 98% of available water on earth, desalination of sea and brackish water is a promising approach to provide clean freshwater for human consumption, irrigation, or industrial use.
Converting seawater into freshwater
There are two main methods for converting seawater into freshwater: desalination technologies based on either thermal processes (such as multiple-effect or multistage flash distillation) or membrane processes (reverse osmosis). Although thermal desalination technologies consume a lot of energy, they have been predominant in the Middle East because the plants are easy to operate and energy costs are low. However, the market trend is turning towards reverse osmosis, even in those regions of low energy costs. Today, more than two thirds of the newly installed desalination capacity worldwide is based on reverse osmosis technology. The benefits of this process: it needs less energy and is more eco-friendly. Sulzer supplies a full range of pumps for sea or brackish water desalination using either reverse osmosis or multiple-effect processes. To follow the market trend, the company has specialized increasingly in equipment for reverse osmosis plants. With the proper plant design and equipment selection, reverse osmosis technology is unbeatable in energy efficiency.
Decreasing costs of reverse osmosis plants
In the reverse osmosis process, seawater is pushed through a membrane. Water molecules permeate through the membrane, but salt particles do not. The part of the seawater that does not cross the membrane—about 55% of the feed flow—is called brine. It is possible to recover energy from the brine. Over the years, the efficiency of energy recovery systems has increased, thus largely reducing life cycle
Pumps also play an important role in decreasing operating expenditures. Since the beginning of development of desalination applications in the 1980s, Sulzer has provided solutions that meet the specific market requirements. In a reverse osmosis plant, Sulzer’s pumps can be used to intake and pretreat seawater, to provide the pressure for the water to diffuse through the membrane, and to transport the freshwater. Because high-pressure pumps use 60% of all the energy consumed in the desalination plant, they need to be highly efficient, reliable, and as low-cost as possible. Each single percentage of their efficiency increase directly lowers the costs of the water produced.
Highly efficient pumps for desalination plants
With this in mind, Sulzer’s teams in Kotka, Finland, and Winterthur, Switzerland, developed the new MBN-RO and MSD-RO pump ranges, which are specifically engineered for reverse osmosis applications. The teams improved the hydraulic efficiency of the pumps by optimizing the suction chamber and the design of the impeller, the diffuser, and the volute. Thanks to their advanced hydraulic design, both the MBN-RO and the MSD-RO are leading products in the market in terms of efficiency. The pumps have already been supplied to several desalination plants in the Middle East and in China. They support the efficient production of potable water for residents as well as of water for industrial processes. Sulzer’s installations around the globe support the production of more than three million m3 of freshwater per day.
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The unique hydraulic design of the SNS pumps ensures extremely efficient pumping in various applications. Engineers in Kotka, Finland, developed this pump range. Watch the video about the new SNS process pump range.
More efficient than required
Because every kilowatt matters with regard to affordable water supply, Sulzer’s engineers developed highly efficient end-suction process pumps. The SNS process pumps, originally designed for the pulp and paper industry, can be used in auxiliary services in seawater reverse osmosis and other applications in the water market. They achieve top-level efficiency, and they exceed the European Union’s requirements for energy-related products by a significant margin. These regulations, which aim to reduce energy consumption, specify the minimum efficiency values for water pumps. The minimum efficiency index (MEI) was set at 0.4 as of the beginning of 2015. Around 40% of the water pumps in use do not comply with this regulation. The SNS process pump range—on the market since 2015—achieved an MEI of 0.7, which is clearly above the required criteria.
Spotting future trends
While regions such as Algeria, Spain, Australia, and the Middle East have built very large plants in the past, the trend is moving to small- and medium-sized plants. They are easier to construct, install, run, and finance. Sulzer supports its customers from a very early project stage in improving the overall efficiency and ensuring the highest possible profitability of the plants. In this way, Sulzer helps provide an affordable and energy-efficient supply of freshwater.