Our New Pump Ranges Address the Needs of the Desalination Market

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Courtesy of Sulzer

Antonio de la Torre is Head of the Engineered Water segment in the Water business unit of Pumps Equipment. He explains the advances in desalination technology and talks about new products and ideas for the future.

Today, more than two-thirds of the newly installed desalination capacity worldwide is based on reverse osmosis technology. Why are customers increasingly choosing this technology?

At first glance, the traditional technologies based on evaporation seem very intuitive. In a distillation process, the seawater is heated up and then separated from the salt by evaporation and condensation. This process is repeated under certain temperature and pressure conditions to increase the process efficiency. Although residual low-pressure steam from a power plant is used for heating, the total amount of energy consumed by this technology is high. Reverse osmosis technology is a membrane process and does not need any thermal energy. Because it is a more complex approach, it offers today a more efficient process, resulting in lower costs of the desalinated water. This is why the market trend is turning towards reverse osmosis, even in those regions where the energy costs are very low, such as in the Middle East.

Reverse osmosis technology has been improved substantially in the last several years. What are the major advances?

In the reverse osmosis process, seawater is pressed through a membrane. Water molecules permeate through the membrane, but salt particles are retained. The part of the seawater that does not cross the membrane, about 55% percent of the feed flow, is called retentate, or brine. It is possible to recover energy from the brine because it still has a high pressure. Over the years, the efficiency of energy recovery systems has been increased significantly. At first, Francis turbines or reverse running pumps were used to recover energy. Later, Pelton turbines took over this job. Several years ago, even-more-efficient energy recovery devices based on isobaric chamber technology were developed. These improvements have reduced the life cycle costs of desalination plants to a great extent, resulting in cheaper and higher-quality desalinated water.

What are the challenges of reverse osmosis technology?

There are three main challenges: the energy efficiency, the brine discharge, and the seawater pretreatment. Pretreatment is necessary, because the membranes are very sensitive to the quality of the seawater. Because they are one of the most expensive components of the plant, it is necessary to protect them by pretreating the seawater thoroughly. Solid particles, polluted content, and biological life need to be removed to prevent fouling and biological growth in the membrane surfaces. This intensive pretreatment can generate more than one-quarter of the total desalination capital and expenditure costs.

How can the costs be further reduced?

Most of the costs in a desalination plant are energy dependent. So the key to success is energy efficiency of all the components. I mentioned the improvements related to the energy recovery devices. Further improvements can come from the pump technology, since each single percentage of their efficiency increase directly lowers the costs of the water produced. With proper plant design and equipment selection, reverse osmosis technology is unbeatable in terms of energy efficiency. We support our customers from a very early stage of the projects in order to optimize the overall efficiency and to ensure the highest possible profitability.

Are these profitable solutions sustainable?

From an environmental point of view, the key aspect is the carbon footprint. By developing technologies that use less energy, we achieve more eco-friendly solutions. But apart from energy consumption, we also need to take care of the brine discharge. The brine has a higher concentration of salt than the seawater, so it is important to ensure proper dilution and to find a suitable location where the brine can be led back to the ocean. That way, sensitive species in the ocean can be protected.

What role does desalination play in Sulzer’s portfolio?

In many regions of the world, the lack of freshwater resources has become a great concern. Desalination is an important means of providing a sustainable supply of freshwater, and it is therefore one of our key markets in the engineered water segment. We are primarily focusing on pumps for reverse osmosis processes but also have activities in the distillation area. Today, we are a full-line pump supplier for reverse osmosis plants. We provide all the pumps for medium-to-large plants: the pumps for seawater intake, pretreatment, high-pressure membrane feed, energy recovery device boosting, and product water transport. Our customers benefit from getting all the pumps from one supplier.

What are the latest developments from Sulzer for the desalination market?

We have focused our development on high-pressure pumps for the reverse osmosis process. These pumps consume around 60% of the energy of the whole plant. We have improved our existing MBN and MSD pumps to address the needs of the desalination market. Recently, we launched the new MBN-RO and MSD-RO pump ranges, which are especially engineered for reverse osmosis applications. Because these pumps do not face any difficult fluids concerning solid content, temperature, or toxicity, the major development issue was efficiency. Today, both the MBN-RO and the MSD-RO are leading products in the market in efficiency.

How did you manage to increase the efficiency?

Our development teams in Karhula (Finland) and Winterthur (Switzerland) improved the hydraulic efficiency by optimizing the suction chamber and the design of the impeller, the diffuser, and the volute. We achieved a higher efficiency not by closing clearances but by having an advanced hydraulic design. Our engineers did an excellent job, and we are clearly beating our competitors in terms of efficiency.

Sulzer has delivered pumps for desalination plants all over the world. Is there a project that you are particularly proud of?

I am really proud of every single project we have worked on. For example, we recently commissioned the Magtaa project in Algeria. At the time of construction, it was the largest desalination plant in the world. We supplied almost all the pumps for that project and had the biggest contract in the desalination market. Thanks to our global network of manufacturing facilities, we managed to deliver the pumps in a short time. The project execution was very smooth, and we established a good partnership with the customer. Another example is the Jubail 4 SWRO project in Saudi Arabia. We have supplied the new MBN-RO pumps and are currently finalizing the construction works.

You are very enthusiastic about desalination technology. What fascinates you about it?

It’s a market that allows you to have technical discussions with customers—and I like that. Generally, in the field of engineered pumps, the technology is highly advanced, and the companies are constantly looking for improvements. I enjoy being involved in the projects at a very early stage and supporting our customers with technical solutions. With this philosophy, Sulzer is not only a pump supplier but is adding value to the whole process.

What are your plans for the future?

We are already experiencing strong activity in the desalination market, but we still want to grow. In addition to the large plants, we also want to focus on smaller plants. The trend is moving from the very large plants that have been built in the past in Algeria, Spain, Australia and the Middle East to small- and medium-sized plants. Smaller plants are much easier to construct, to install, to operate, and especially to finance. We want to push this market trend. Ultimately, our goal is to be the number one in the desalination market.

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