oil or grease . That saves operators the expense and complexity of forced oil lubrication systems , reduces the risk of product contamination and enables state-of-the-art efficiency without compromising reliability .
Improvements in hydraulic performance have been achieved by replacing axial split casing pumps with ring section designs . Initially , this approach was only applied to smaller RO trains , but these pumps are now available with capacities of up to 1 ’ 000 m3 per hour for larger trains .
Hydraulic improvements came also in low pressure applications , where traditionally single stage , double suction pumps were traditionally used . Today , even at higher capacities , users are now choosing cost-effective end suction overhung pump designs with higher efficiencies and extremely good suction performance in a highly reliable way .
Pump control technology has improved dramatically too , thanks to the availability of reliable and cost-effective variable speed drives . These give users the flexibility to run pumps over a wider range of operating conditions , minimizing the need to regulate flows via valve throttling . They also allow pumps to operate closer to their best efficiency point , avoiding unnecessary impeller trims that can have a negative impact on overall efficiency . While the first variable speed drives used in the industry were affordable only for low voltage drivers for low pressure pumps , the availability of medium voltage drives has extended the benefits of this approach to high-pressure pumps .
Economies of scale Perhaps the most important driver of improved pump efficiency in RO plants
A choice of pump designs ensure the most efficient solution for each project
leading to substantially reduced specific consumption has been scale , since the efficiency of a centrifugal pump increases with its capacity . The first opportunity to capture scale advantages came with the introduction of larger RO trains , which increased from a maximum of 15 ’ 000 m3 per day in 2001 , to 25 ’ 000 or even 30 ’ 000 m3 per day .
The next opportunity came from a change in system architecture . The creation of the Pressure Center concept allowed the introduction of very large pumps that supply multiple RO trains through a manifold system . Plants using this design were first introduced in the mid-2000s and it has since become the standard approach for large SWRO facilities .
Sulzer has been supplying high pressure pumps for such Pressure Center concepts from the beginning . Utilizing a twostage solution , the high-pressure pumps used in those first Pressure Center facilities had a high-pressure flow of around 2 ’ 500 m3 per hour and achieved efficiencies of around 88 %. Today , Sulzer is delivering high-pressure pumps for the largest plants with capacities in the range of 3 ’ 500 to 4 ’ 000m3 per hour and efficiencies above 90 %.
While efficiency improvements on the high-pressure pump are getting close to the physical limits , potential improvements are coming from other pumps services in a SWRO plant . This performance is being matched by the company ’ s latest low-pressure end suction pumps , used in other continuous services like the intermediate , the lowpressure booster or the second pass pumps , which can also achieve efficiency ratings of more than 90 %.
The desalination sector is continually advancing , with incremental improvements in scale , efficiency and reliability . Each new project aims to reach the limits of performance , and every year the sector finds ways to push those limits just a little further . As a leading player in the pump industry and a longstanding partner to the sector , Sulzer is proud to play its own part in that ongoing improvement process . Ultimately , everyone has one common goal : delivering more affordable fresh water to the people that need it most .
For more information , visit www . sulzer . com
Sulzer ’ s design and manufacturing expertise tailors each pump to its application
As a leading pump specialist , Sulzer has decades of experience in the RO sector
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