Technical Overview
In thermal and nuclear power generation, water is the primary medium for energy transfer and cooling. The integrity of the steam-water cycle is mission-critical; even trace levels of impurities can lead to catastrophic failure through corrosion, scaling, or deposition on turbine blades.
High-Purity Boiler Feed Water
Modern high-pressure boilers and Once-Through Steam Generators (OTSG) require ultrapure water. The treatment train typically involves Ultrafiltration (UF) for particle removal, followed by two-pass Reverse Osmosis (RO) and polishing via Continuous Electrodeionization (CEDI) or mixed-bed ion exchange. The primary goal is the near-total removal of Silica (SiO2), which can volatilize in the boiler and deposit as a glass-like scale on turbines, and Oxygen (O2), which facilitates localized pitting corrosion.
Cooling Water Management
Cooling systems represent the largest volume of water used in power plants. Managing cooling tower chemistry involves balancing the Cycles of Concentration (COC) to minimize blowdown while preventing scaling from calcium carbonate and magnesium silicate. Biofouling control is equally vital, as biofilms create significant heat transfer resistance and can harbor Legionella. Advanced oxidation and non-oxidizing biocides are often used in rotation to manage microbial populations.
ZLD and Flue Gas Desulfurization (FGD)
Power plants are increasingly required to implement Zero Liquid Discharge (ZLD) to manage wastewater from Flue Gas Desulfurization (FGD). FGD wastewater is particularly challenging due to high concentrations of chlorides, selenium, nitrates, and mercury. Treatment often involves chemical precipitation, biological selenium removal, and ultimately, thermal evaporation/crystallization. As regulations like the EPA Effluent Limitation Guidelines (ELG) tighten, the adoption of ZLD is transitioning from a site-specific choice to an industry-wide mandate for new and retrofitted plants.