Seawater Reverse Osmosis Plants

In Reverse Osmosis (RO), a key set of valves is installed in the high pressure area between High Pressure (HP) pumps and membranes where pressure can reach up to 80 bar and the chlorine content of water is extremely high. In these conditions, super austenitic stainless steels such as Duplex type 5A (with PREN >42) are usually utilized to handle corrosion. However, these valves face further challenges for which they often become one of the main weakness point of the entire line. In fact, while high pressure valves must isolate and provide tight shut-off during single RO blocks (including bidirectional isolation whenever necessary), they are also required to control pressure during pump start-ups to ensure that pressure rises smoothly inside the membranes.

Application: One of the most successful methods to desalinate water is through Sea Water Reverse Osmosis (SWRO).

Challenges: SWRO plants are extremely dependent on the effectiveness of the water's pre-treatment and may require larger amounts of energy compared to traditional methods. Thus, end users are reassessing valve performance and looking for alternatives to improve overall plant efficiency. Emerson is able to provide a valid solution to solve the usual issues arising from traditional valve use and help customers achieve their goals. Vanessa Series 30,000, for one, is a robust, durable and reliable valve capable of reducing failure rate to virtually zero and maximizing the return on capital investment. Its high safety integrity levels also allow for complete protection of high pressure pumps through the adoption of other critical functions such as main pump isolation and, with suitable actuation systems, a combination of isolation and non-return.