EDI for Power Plants -- Importance of silica


Courtesy of SnowPure Water Technologies

Power plants use high purity water to drive steam turbines. Cogeneration plants are highly efficient, using both exhaust turbines and high pressure steam turbines.

In the 1960's, boilers operated at 450C (840F) and 4MPa (40 atmospheres). Today's leading edge boilers operate at 620C (1150F) and 30MPa (300 atmospheres).

To keep power efficiency high, maximize uptime, and minimize turbine maintenance, boiler makeup water must be ultrapure (17+ Megohm.cm) and have very little silica (SiO2). Silica levels required are in the range of 5-20 ppb, depending on the boiler pressure. Under the boiler/turbine conditions, dissolved silica will form a glass on surfaces like the turbine blades.

Mixed Bed DI technology is a batch process, and requires duplex towers. There can be a spike in silica whenever the MB's are swapped. Electrodeionization (EDI) does not have this problem.

Today, state of the art boiler water makeup uses RO-GTM-EDI to achieve continuous low levels of silica feeding the boiler system. 1-5 ppb silica is achievable with the proper components and system design.

Click here to explore EDI for Boiler Water Makeup

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